Island microgrid secondary control method based on proportional fragment integral, medium and equipment

Abstract

The invention discloses an island micro-grid secondary control method based on proportional fragment integral, a medium and equipment, and relates to the field of intelligent power grid control, and the island micro-grid secondary control method based on proportional fragment integral mainly comprises the steps: setting a droop controller according to a micro-grid to be controlled, and constructing a control target; constructing a distributed generator large-signal dynamic model according to the droop controller and the micro-grid to be controlled, and constructing a controller parameter stability criterion and a feasibility condition for a stability problem of a stochastic differential equation; and obtaining a control parameter according to a controller parameter stability criterion and a feasibility condition. By implementing the island microgrid secondary control method based on proportional fragment integral, the medium and the equipment provided by the invention, coordinated control among distributed generators can be realized, and the robustness of the microgrid in a noise environment is improved.

Description

Technical Field

[0001] The present invention relates to the field of smart grid control, and more specifically, to an island microgrid secondary control method, medium and device based on proportional segment integration. Background Art

[0002] The environmental problems and energy crisis caused by the consumption of fossil energy have formed a huge conflict with people's growing demand for electricity. In order to alleviate this situation, the trend of vigorously developing new energy such as wind energy and solar energy is inevitable. In order to improve the large power grid's capacity to accommodate renewable energy, connecting distributed power sources to the distribution network in the form of microgrids is generally considered to be one of the effective ways to utilize distributed power sources. A microgrid is a low-voltage distribution network composed of distributed generators (DG), energy storage systems and loads. It can be connected to the main grid at a point called PCC (point of common coupling). The microgrid can be connected to the grid or in an island mode. In the grid-connected mode, the frequency and voltage of the microgrid are controlled by the main grid; in the island mode, the voltage and frequency will lose the support of the main grid, and the active power between the power source and the load will be unbalanced, so the main control goal is to keep the frequency and voltage stable to the reference value and accurate power sharing.

[0003] In order to solve these problems, hierarchical control is generally adopted, including a three-layer theoretical model. Primary control usually uses a droop controller and an inner control loop to maintain the stability of voltage and frequency, but droop control will cause the voltage and frequency of the microgrid to deviate from their reference values. In order to compensate for these deviations, secondary control is used to restore frequency and voltage. The traditional secondary control method adopts a centralized structure. The centralized controller requires all information of each DG unit and a complex communication network, which is prone to single point failure and has low reliability. Distributed collaborative control only requires neighborhood information and a sparse communication network, which provides conditions for the "plug and play" of distributed power sources, improves the reliability of the system, and reduces costs, but at the same time it is highly dependent on communication. The stability of the microgrid faces severe challenges under the unreliable factors of the communication network.

[0004] In practical applications, distributed control requires information exchange between adjacent nodes, which inevitably involves some uncertain factors, such as time delay and different types of noise, which can damage the communication channel and affect the stability of the microgrid. In recent years, the problem of distributed cooperative control of microgrids in ideal environments has become increasingly mature, and scholars have achieved some fruitful results. However, research on microgrid control in noisy environments is very limited, and distributed cooperative control of microgrids still faces great challenges. Therefore, it is necessary to develop a distributed secondary control method for isolated island microgrids in noisy environments. Summary of the invention

[0005] The object of the present invention is to provide an island microgrid secondary control method, medium and device based on proportional segment integration, which can realize coordinated control between distributed generators and improve the robustness of the microgrid in a noisy environment.

[0006] The present invention provides an island microgrid secondary control method based on proportional segment integration, comprising the following steps: S1: according to the microgrid to be controlled, a droop controller is set to construct a control target; S2: according to the droop controller and the microgrid to be controlled, a large signal dynamic model of a distributed generator is constructed; S3: according to the large signal dynamic model of the distributed generator, an input-output feedback linearization method is used to obtain a system linear model; according to the system linear model, a proportional segment integration control protocol is constructed;

[0007] S4: According to the proportional-segment-integral control protocol and the control objective, the voltage consistency problem in the multiplicative noise environment is transformed into the stability problem of the stochastic differential equation, and the stochastic differential equation of the closed-loop system is obtained; S5: According to the stochastic differential equation of the closed-loop system, the controller parameter stability criterion and feasibility condition are constructed, and the controller parameter stability criterion and feasibility condition are used to achieve the stability of the stochastic differential equation of the closed-loop system; S6: According to the controller parameter stability criterion and feasibility condition, the voltage control parameters are obtained; S7: According to the droop controller, the control objective and the microgrid to be controlled, the frequency secondary control protocol and the sufficient conditions for the mean square consistency of the output frequency of the distributed generator set are constructed to obtain the frequency control parameters.

[0008] Furthermore, the step S1 of the above-mentioned isolated microgrid secondary control method based on proportional segment integration specifically includes: S11: according to the microgrid to be controlled, setting the droop controller of the primary control of the microgrid to be controlled, such as formula:

[0009]

[0010] Among them, ω i is the frequency of the ith generator, ω ni is the reference value in the primary control of the i-th generator to be designed in the secondary control layer, m Pi represents the active power droop coefficient of the i-th generator, P i is the low-pass filtered value of the active power output by the ith generator, v oi.mag is the output voltage amplitude of the ith generator, v ni is the reference value in the primary control of the i-th generator to be designed in the secondary control layer, n Qi represents the reactive power droop coefficient of the i-th generator, Q i is the low-pass filtered value of the reactive power output by the i-th generator;

[0011] S12: According to the microgrid to be controlled, a control target of the secondary control of the microgrid to be controlled is constructed, such as the formula:

[0012]

[0013] Among them, ω i (t) is the frequency of the i-th generator, ω ref is the nominal frequency, m Pi represents the active power droop coefficient of the i-th generator, P i (t) is the low-pass filtered value of the active power output by the ith generator, m Pj represents the active power droop coefficient of the jth generator, P j (t) is the low-pass filtered value of the active power output by the jth generator, v oi.mag (t) is the output voltage amplitude of the ith generator, v ref is the nominal voltage, i and j are the serial numbers of the distributed generators.

[0014] Furthermore, step S2 of the above-mentioned isolated microgrid secondary control method based on proportional segment integration specifically includes: constructing a large signal dynamic model of a distributed generator according to the droop controller and the microgrid to be controlled, such as the formula:

[0015]

[0016] x i =[δ i , P i , Q i ,i ldi ,i lqi , v odi , v oqi ,i odi ,i oqi ] T ,

[0017] u i =[u i1 ,u i2 ] T =[v ni ,ω ni ] T ,

[0018] y i =[y i1 ,y i2 ] T =[v odi ,ω i ] T ,

[0019] D i =[ω com , vbdi , v bqi ] T ,

[0020]

[0021] g i1 (x i )=v odi , g i2 (x i )=-m Pi P i , d i =1,

[0022]

[0023] in, is the time derivative of the state of the ith generator, x i is the state of the i-th generator, δ i is the angle of the i-th distributed generation reference system relative to the common reference system, P i is the low-pass filter value of the output active power, Q i is the low-pass filter value of the output reactive power, i ldi and i lqi Respectively represent i li The d-axis component and q-axis component of odi and ν oqi Respectively represent ν oi The d-axis component and q-axis component of i odi and i oqi Respectively represent i oi The d-axis component and q-axis component of v bdi and v bqi Respectively represent ν bi The d-axis component and q-axis component of i li represents the inverter output current of the ith distributed power source, v oi represents the output voltage of the i-th distributed power source, i oi represents the output current of the i-th distributed power source, v bi represents the bus voltage of the ith distributed generation, D i is the known interference vector, ω com is the frequency interference, f i (x i ), k i (x i ), r i1 (x i ), r i2 (x i ), g i1 (x i), g i2 (x i ), d i is the intermediate vector, u i is the input vector of the ith generator, u i1 and u i2 is the input of the ith generator, y i is the output vector of the ith generator, y i1 and i2 is the output of the ith generator, ω i is the frequency of the ith generator, ω ni is the reference value in the primary control to be designed in the secondary control layer, m Pi Indicates the active power droop coefficient, ν ni is the reference value in the primary control to be designed in the secondary control layer, ω ci is the cutoff frequency of the low-pass filter, L fi , R fi , C fi are the inductance, resistance and capacitance of the LC filter, L ci , R ci is the inductance and resistance of the output connector, ω com is the common angular frequency of the distributed power source.

[0024] Furthermore, step S3 of the above-mentioned island microgrid secondary control method based on proportional segment integration specifically includes:

[0025] S31: According to the large signal dynamics model of the distributed generator, the nonlinear system is transformed using the input-output feedback linearization method to obtain the system linear model, as shown in the formula:

[0026]

[0027]

[0028]

[0029] λ(A)=0,

[0030]

[0031]

[0032]

[0033]

[0034]

[0035] F i =fi (x i )+k i (x i )D i ,

[0036] in, is the derivative of the output vector of the ith generator, A and B are constant matrices, ν i is the auxiliary input voltage, v odi The derivative of y i1,2 for λ(A) is the eigenvalue of matrix A, y0 is the leader output, is the derivative of y0, v ref is the nominal voltage, v ref The derivative of ni is the control input voltage, Represents r i1 The Li derivative of Representatives of F i The Li derivative of for y i1 The second derivative of i F i =f i (x i )+k i (x i )D i ;

[0037] S32: According to the system linear model, a proportional-segment-integral control protocol is constructed, such as the formula:

[0038]

[0039] z 1ji (t) = y j1 (t)-y i1 (t)+f 1ji (y j1 (t)-y i1 (t))ξ 1ji (t)

[0040] z 2ji (t) = y j1，2 (t)-y i1，2 (t)+f 2ji (y j1，2 (t)-y i1，2 (t))ξ 2ji (t)

[0041] Among them, v i (t) is the auxiliary input voltage, kp1 , k p2 is the proportional feedback gain to be designed, N i is the neighbor of the ith generator, z 1ji is the voltage measured by the i-th DG from its neighbor j-th DG, k i1 , k i2 is the integral feedback gain to be designed, h is the length of the segment integral, z 2ji is the derivative of the voltage measured by the ith DG from its neighbor, the jth DG.

[0042] Furthermore, step S4 of the above-mentioned island microgrid secondary control method based on proportional segment integration specifically includes: according to the proportional segment integration control protocol and the control target, the voltage consistency problem in the multiplicative noise environment is converted into a stability problem of the stochastic differential equation, and the closed-loop system stochastic differential equation is obtained, such as the formula:

[0043]

[0044] in,

[0045]

[0046] M 12 (t) = M1(t) + M2(t),

[0047] M 34 (t) = M3(t) + M4(t),

[0048]

[0049] δ1(t)=[δ 11 (t),…,δ 1N (t)] T ,δ2(t)=[δ 1，21 (t),…,δ 1，2N (t)] T ,

[0050]

[0051]

[0052] B 1ji (t) = [0 b 1ji (t) T ] T , B 2ji (t) = [0 b 2ji (t) T ] T ,

[0053] b1ji (t)=Φ(i)f 1ji (δ 1j (t)-δ 1i (t)),

[0054] b 2ji (t)=Φ(i)f 2ji (δ 1，2j (t)-δ 1，2i (t)),

[0055]

[0056] in, is the system error vector, for The differential of , h is the length of the fragment integral, the intermediate variable in the calculation process of A1 and A2, is the error vector of the system during the integration time, Λ0 is Λ0=diag(λ 01 , ..., λ 0N ), λ 0i represents the Laplacian matrix The characteristic value of I N is the N-order unit matrix, M 12 (t), M 34 (t), M1(t), M2(t), M3(t), and M4(t) are all random differential equation noise terms, N is the number of followers, and a ij is an element in the adjacency matrix, a ij is not equal to 0, it means that there is information flow from j to i, otherwise, a ij =0; B 1ji (t), B 2ji (t), b 1ji (t) and b 2ji (t) are: B 1ji (t) = [0 b 1ji (t) T ] T , B 2ji (t) = [0 b 2ji (t) T ] T , b 1ji (t)=Φ(i)f 1ji (δ 1j (t)-δ 1i (t)), b 2ji =Φ(i)f 2ji (δ 1，2j (t)-δ 1，2i (t)), B 1ji (s) and B 2ji(s) are B in the integral time 1ji (t) and B 2ji (t), w 1ji (s) and w 2ji (s) are defined in the complete probability space The independent two-dimensional Brownian motion on , Φ(i) is , represents an N-order column vector, the i-th element is 1 and the rest are all 0, φ is an orthogonal matrix, δ 1i (t) is δ 1i (t) = y 1i (t)-y 10 (t), y 1i (t) is ν odi ,y 10 (t) is the leader's ν odi , δ 1,2i (t) is y 1,2i (t) is v odi The time derivative, v for leaders odi The time derivatives, δ1(t) and δ2(t), are δ1(t)=[δ 11 (t),…,δ 1N (t)] T ,δ2(t)=[δ 1，21 (t),…,δ 1，2N (t)] T ,, for g=1 or 2, Ф T is the transpose of the matrix Φ, and are the transpose of the corresponding matrices, f 1ji (.) and f 2ji (.) is the noise intensity function; δ 1j (t) Same meaning as δ 1i (t), the difference is the sequence number; δ 1,2j (t) Same meaning as δ 1,2i (t), the difference is the sequence number.

[0057] Furthermore, step S5 of the above-mentioned island microgrid secondary control method based on proportional segment integration specifically includes: constructing controller parameter stability criteria and feasibility conditions according to the closed-loop system stochastic differential equation, and the controller parameter stability criteria and feasibility conditions are used to achieve the stability of the closed-loop system stochastic differential equation, such as formula:

[0058]

[0059]

[0060]

[0061] in, is the transpose of the matrix Ah, A h is the intermediate variable in the calculation process, P is a positive definite matrix, ε1, ε2 and ε3 are constants, h is the length of the fragment integral, is the transpose of matrix A2, A2 is U1 is U2 is Λ0 is Λ0=diag(λ 01 , ..., λ 0N ), I N is the N-order unit matrix, μ and θ are the parameters to be designed, and is the maximum value of the noise intensity.

[0062] Furthermore, step S7 of the above-mentioned isolated microgrid secondary control method based on proportional segment integration specifically includes: S71: constructing a frequency secondary control protocol according to the droop controller, the control target and the microgrid to be controlled; S72: obtaining a sufficient condition for the mean square consistency of the output frequency of the distributed generator set according to the frequency secondary control protocol; S73: obtaining a frequency control parameter according to the sufficient condition for the mean square consistency of the output frequency of the distributed generator set.

[0063] Furthermore, step S71 of the above-mentioned island microgrid secondary control method based on proportional segment integration specifically includes: constructing a frequency secondary control protocol according to the droop controller, the control target and the microgrid to be controlled, such as formula:

[0064]

[0065]

[0066] ω ni =∫(u ωi +u Pi )dt,

[0067] Among them, u ωi (t) is the input of frequency control, k ωp , k ωi are the proportional term and integral term feedback gains to be designed in the frequency control protocol, N i is the neighbor of the i-th distributed generation, z ωji (t) and z ωji (s) is the frequency measured by the ith distributed generator from its neighboring jth distributed generator, u Pi (t) is the input of power control, K Pp , kPi are the proportional term and integral term feedback gains to be designed in the power control protocol, respectively, Pji (t) and z Pji (s) is the power measured by the i-th distributed generator from its neighbor j-th distributed generator, ω ni ω is the frequency control ni is the reference value in the primary control of the i-th generator to be designed at the secondary control level;

[0068] Step S72 specifically includes: according to the frequency secondary control protocol, obtaining the sufficient condition for the mean square consistency of the output frequency of the distributed generator set, such as the formula:

[0069]

[0070]

[0071] Among them, ε1, ε2 and ε3 are constants, are the maximum values ​​of noise intensity.

[0072] The present invention also provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the above-mentioned isolated island microgrid secondary control method based on proportional segment integration are implemented.

[0073] The present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the steps of the above-mentioned isolated island microgrid secondary control method based on proportional segment integration are implemented.

[0074] The implementation of the isolated island microgrid secondary control method, medium and device based on proportional segment integration provided by the present invention has the following beneficial effects:

[0075] The present invention is aimed at a microgrid system including multiple distributed generators. Each distributed generator uses its own information and the information of other distributed generators that can exchange information with it to briefly analyze the primary control and secondary control of the microgrid and clarify the control target; establish a large signal dynamic model of the distributed generator; use the input-output feedback linearization method to convert the nonlinear system of the microgrid into a linearized system, and design a proportional fragment integral (PFI) control protocol similar to PI control to eliminate the voltage and frequency deviations with multiplicative noise in the communication layer; according to the control protocol, the voltage and frequency consistency problem in the multiplicative noise environment is converted into the stability problem of the stochastic differential equation driven by multiplicative noise; construct the mean square consistent stability criterion and the almost inevitable consistent stability criterion about the controller parameters, as well as the feasibility conditions for realizing voltage and frequency synchronization; select appropriate control parameters such as PFI control gain for the proposed stability criterion and feasibility conditions, so that the output voltage amplitude and frequency of all distributed generators track the leader reference value, and realize the accurate distribution of active power at the same time, further compensate for the deviation caused by the primary control, maintain reasonable active power sharing, and improve the robustness of the microgrid in the noise environment, thereby ensuring the stability of the microgrid. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0077] Figure 1 It is a flow chart of the secondary control method of an isolated island microgrid based on proportional segment integration provided by the present invention;

[0078] Figure 2 It is a typical structure diagram of a distributed generator based on an inverter in an island mode provided by the present invention;

[0079] Figure 3 is a communication topology relationship diagram between the distributed generators provided by the present invention;

[0080] Figure 4 It is a structural diagram of a microgrid provided by the present invention;

[0081] Figure 5 It is a graph showing the change in the output voltage amplitude of the distributed generator provided by the present invention;

[0082] Figure 6 It is a graph showing the output frequency variation of the distributed generator provided by the present invention;

[0083] Figure 7 It is a graph showing changes in the output active power of the distributed generator provided by the present invention;

[0084] Figure 8 It is a structural block diagram of the computer device provided by the present invention. DETAILED DESCRIPTION

[0085] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0086] Figure 1 A schematic diagram of the isolated island microgrid secondary control method based on proportional segment integration of this embodiment is shown; in this embodiment, the isolated island microgrid secondary control method based on proportional segment integration includes the following steps:

[0087] S1: According to the microgrid to be controlled, a droop controller is set to build a control target;

[0088] Specifically, step S1 includes:

[0089] S11: According to the microgrid to be controlled, a droop controller for the primary control of the microgrid to be controlled is set, such as the formula:

[0090]

[0091] Among them, ω i is the frequency of the ith generator, ω ni is the reference value in the primary control of the i-th generator to be designed in the secondary control layer, m Pi represents the active power droop coefficient of the i-th generator, P i is the low-pass filtered value of the active power output by the ith generator, v oi.mag is the output voltage amplitude of the ith generator, v ni is the reference value in the primary control of the i-th generator to be designed in the secondary control layer, n Qi represents the reactive power droop coefficient of the i-th generator, Q i is the low-pass filtered value of the reactive power output by the i-th generator;

[0092] S12: According to the microgrid to be controlled, a control target of the secondary control of the microgrid to be controlled is constructed, such as the formula:

[0093]

[0094] Among them, ω i (t) is the frequency of the i-th generator, ω ref is the nominal frequency, m Pi represents the active power droop coefficient of the i-th generator, P i (t) is the low-pass filtered value of the active power output by the ith generator, m Pj represents the active power droop coefficient of the jth generator, P j (t) is the low-pass filtered value of the active power output by the jth generator, v oi.mag (t) is the output voltage amplitude of the ith generator, vref is the nominal voltage, i and j are the serial numbers of the distributed generators;

[0095] S2: Based on the droop controller and the microgrid to be controlled, a large signal dynamic model of the distributed generator is constructed;

[0096] Specifically, step S2 includes: constructing a large signal dynamic model of a distributed generator according to the droop controller and the microgrid to be controlled, such as the formula:

[0097]

[0098] x i =[δ i , P i , Q i ,i ldi ,i lqi , v odi , v oqi ,i odi ,i oqi ] T ,

[0099] u i =[u i1 ,u i2 ] T =[v ni ,ω ni ] T ,

[0100] y i =[y i1 ,y i2 ] T =[v odi ,ω i ] T ,

[0101] D i =[ω com , v bdi , v bqi ] T ,

[0102]

[0103] g i1 (x i )=v odi , g i2 (x i )=-m Pi P i , d i =1,

[0104]

[0105] in, is the time derivative of the state of the ith generator, x i is the state of the i-th generator, δ i is the angle of the i-th distributed generation reference system relative to the common reference system, P i is the low-pass filter value of the output active power, Q i is the low-pass filter value of the output reactive power, i ldi and i lqi Respectively represent i li The d-axis component and q-axis component of v odi and v oqi Respectively represent ν oi The d-axis component and q-axis component of i odi and i oqi Respectively represent i oi The d-axis component and q-axis component of bdi and ν bqi Respectively represent ν bi The d-axis component and q-axis component of i li represents the inverter output current of the ith distributed power source, v oi represents the output voltage of the i-th distributed power source, i oi represents the output current of the i-th distributed power source, v bi represents the bus voltage of the ith distributed generation, D i is the known interference vector, ω com is the frequency interference, f i (x i ), k i (x i ), r i1 (x i ), r i2 (x i ), g i1 (x i ), g i2 (x i ), d i is the intermediate vector, u i is the input vector of the ith generator, u i1 and u i2 is the input of the ith generator, y i is the output vector of the ith generator, y i1 and i2 is the output of the ith generator, ω i is the frequency of the ith generator, ω ni is the reference value in the primary control to be designed in the secondary control layer, m Pi Indicates the active power droop coefficient, ν niis the reference value in the primary control to be designed in the secondary control layer, ω ci is the cutoff frequency of the low-pass filter, L fi , R fi , C fi are the inductance, resistance and capacitance of the LC filter, L ci , R ci is the inductance and resistance of the output connector, ω com is the common angular frequency of distributed power sources;

[0106] S3: Based on the large signal dynamics model of the distributed generator, the system linear model is obtained by using the input-output feedback linearization method; based on the system linear model, the proportional-fraction-integral control protocol is constructed;

[0107] Specifically, step S3 includes:

[0108] S31: According to the large signal dynamics model of the distributed generator, the nonlinear system is transformed using the input-output feedback linearization method to obtain the system linear model;

[0109] Specifically, step S31 includes: according to the large signal dynamics model of the distributed generator, using the input-output feedback linearization method, converting the nonlinear system to obtain a system linear model, such as formula:

[0110]

[0111]

[0112]

[0113] λ(A)=0,

[0114]

[0115]

[0116]

[0117]

[0118]

[0119] in, is the derivative of the output vector of the ith generator, A and B are constant matrices, ν i is the auxiliary input voltage, v odi The derivative of y i1,2 for λ(A) is the eigenvalue of matrix A, y0 is the leader output, is the derivative of y0, v ref is the nominal voltage, v ref The derivative of ni is the control input voltage, Represents r i1 The Li derivative of Representatives of F i The Li derivative of for y i1 The second derivative of i F i =f i (x i )+k i (x i )D i ;

[0120] S32: Based on the system linear model, a proportional-segment-integral control protocol is constructed;

[0121] Specifically, step S32 includes: constructing a proportional segment integral control protocol according to the system linear model, such as the formula:

[0122]

[0123] z 1ji (t) = y j1 (t)-y i1 (t)+f 1ji (y j1 (t)-y i1 (t))ξ 1ji (t)

[0124] z 2ji (t) = y j1，2 (t)-y i1，2 (t)+f 2ji (y j1，2 (t)-y i1，2 (t))ξ 2ji (t)

[0125] Among them, v i (t) is the auxiliary input voltage, k p1 , k p2 is the proportional feedback gain to be designed, N i is the neighbor of the ith generator, z 1ji is the voltage measured by the i-th distributed generator from its neighbor, the j-th distributed generator, k i1 , k i2 is the integral feedback gain to be designed, h is the length of the segment integral, z 2jiis the derivative of the voltage measured by the ith DG from its neighbor, the jth DG;

[0126] S4: According to the proportional-segment-integral control protocol and the control target, the voltage consistency problem under the multiplicative noise environment is transformed into the stability problem of the stochastic differential equation, and the stochastic differential equation of the closed-loop system is obtained;

[0127] Specifically, step S4 includes: according to the proportional-segment-integral control protocol and the control target, converting the voltage consistency problem in the multiplicative noise environment into the stability problem of the stochastic differential equation, and obtaining the closed-loop system stochastic differential equation, such as the formula:

[0128]

[0129]

[0130] M 12 (t) = M1(t) + M2(t),

[0131] M 34 (t) = M3(t) + M4(t),

[0132]

[0133]

[0134] δ1(t)=[δ 11 (t),…,δ 1N (t)] T ,δ2(t)=[δ 1，21 (t),…,δ 1，2N (t)] T ,

[0135]

[0136] g = 1, 2,

[0137]

[0138] B 1ji (t) = [0 b 1ji (t) T ] T , B 2ji (t) = [0 b 2ji (t) T ] T ,

[0139] b 1ji (t)=Φ(i)f 1ji (δ 1j (t)-δ1i (t)),

[0140] b 2ji (t)=Φ(i)f 2ji (δ 1，2j (t)-δ 1，2i (t)),

[0141] in, is the system error vector, for The differential of , h is the length of the fragment integral, the intermediate variable in the calculation process of A1 and A2, is the error vector of the system during the integration time, Λ0 is Λ0=diag(λ 01 , ..., λ 0N ), λ 0i represents the Laplacian matrix The characteristic value of I N is the N-order unit matrix, M 12 (t), M 34 (t), M1(t), M2(t), M3(t), and M4(t) are all random differential equation noise terms, N is the number of followers, and a ij is an element in the adjacency matrix, a ij is not equal to 0, it means that there is information flow from j to i, otherwise, a ij =0; B 1ji (t), B 2ji (t), b 1ji (t) and b 2ji (t) are: B 1ji (t) = [0 b 1ji (t) T ] T , B 2ji (t) = [0 b 2ji (t) T ] T , b 1ji (t)=Φ(i)f 1ji [δ 1j (t)-δ 1i ((t)), b 2ji (t)=Φ(i)f 2ji [δ 1，2j (t)-δ 1，2i ((t)), B 1ji (s) and B 2ji (s) are B in the integral time 1ji (t) and B 2ji (t), w 1ji (s) and w 2ji (s) are defined in the complete probability space The independent two-dimensional Brownian motion on , Φ(i) is represents an N-order column vector, the i-th element is 1 and the rest are all 0, Φ is an orthogonal matrix, δ 1i (t) is δ 1i (t) = y 1i (t)-y 10 (t), y 1i (t) is v odi ,y 10 (t) is the leader's v odi , δ 1,2i (t) is y 1,2i (t) is v odi The time derivative, v for leaders odi The time derivatives, δ1(t) and δ2(t), are δ1(t)=[δ 11 (t),…,δ 1N (t)] T ,δ2(t)=[δ 1，21 (t),…,δ 1，2N (t)] T , for g=1 or 2, Ф T is the transpose of the matrix Φ, and are the transpose of the corresponding matrices, f 1ji (.) and f 2ji (.) is the noise intensity function; δ 1j (t) Same meaning as δ 1i (t), the difference is the sequence number; δ 1,2j (t) Same meaning as δ 1,2i (t), the difference is the serial number;

[0142] S5: According to the stochastic differential equation of the closed-loop system, the controller parameter stability criterion and feasibility condition are constructed, and the controller parameter stability criterion and feasibility condition are used to achieve the stability of the stochastic differential equation of the closed-loop system;

[0143] Specifically, step S5 includes: constructing controller parameter stability criteria and feasibility conditions according to the closed-loop system stochastic differential equation, and the controller parameter stability criteria and feasibility conditions are used to achieve the stability of the closed-loop system stochastic differential equation, such as formula:

[0144]

[0145]

[0146] in, is the transpose of the matrix Ah, A h is the intermediate variable in the calculation process, P is a positive definite matrix, ε1, ε2 and ε3 are constants, h is the length of the fragment integral, is the transpose of matrix A2, A2 is U1 is U2 is Λ0 is Λ0=diag(λ 01 , ..., λ 0N ), I N is the N-order unit matrix, μ and θ are the parameters to be designed, and is the maximum value of noise intensity;

[0147] S6: Obtain voltage control parameters according to controller parameter stability criteria and feasibility conditions;

[0148] Specifically, we select k p1 =3, k i1 =5, k p2 =10, k i2 =15 is the control gain, θ=1, h=0.01, The proposed stability criteria and feasibility conditions are met to achieve voltage synchronization of each distributed generator to the reference value;

[0149] S7: According to the droop controller, the control target and the microgrid to be controlled, the frequency secondary control protocol and the sufficient condition for the mean square consistency of the output frequency of the distributed generator set are constructed to obtain the frequency control parameters;

[0150] Specifically, step S7 includes:

[0151] S71: construct a frequency secondary control protocol according to the droop controller, the control target and the microgrid to be controlled;

[0152] Specifically, step S71 includes: constructing a frequency secondary control protocol according to the droop controller, the control target and the microgrid to be controlled, such as the formula:

[0153]

[0154]

[0155] ω ni =∫(u ωi +u Pi )dt,

[0156] Among them, u ωi (t) is the input of frequency control, k ωp , k ωiare the proportional term and integral term feedback gains to be designed in the frequency control protocol, N i is the neighbor of the i-th distributed generation, z ωji (t) and z ωji (s) is the frequency measured by the ith distributed generator from its neighboring jth distributed generator, u Pi (t) is the input of power control, k Pp , k Pi are the proportional term and integral term feedback gains to be designed in the power control protocol, respectively, Pji (t) and z Pji (s) is the power measured by the i-th distributed generator from its neighbor j-th distributed generator, ω ni ω is the frequency control ni is the reference value in the primary control of the i-th generator to be designed at the secondary control level;

[0157] S72: According to the frequency secondary control protocol, a sufficient condition for the mean square consistency of the output frequency of the distributed generator set is obtained;

[0158] Specifically, step S72 includes: according to the frequency secondary control protocol, obtaining the sufficient condition for the mean square consistency of the output frequency of the distributed generator set, such as the formula:

[0159]

[0160] Among them, ε1, ε2 and ε3 are constants, are the maximum values ​​of noise intensity;

[0161] S73: Obtain frequency control parameters according to the sufficient condition for mean square consistency of output frequencies of the distributed generator sets;

[0162] Specifically, select K ωp =3, k ωi =5, k Pp =3, k Pi =5, h=0.01, The proposed sufficient condition for the mean square consistency of the output frequency of the distributed generator sets is met, and the frequency synchronization is restored to the reference value and the active power is accurately shared.

[0163] In some embodiments, the above-mentioned isolated island microgrid secondary control method based on proportional segment integration can also be implemented in the following manner. In this embodiment, the isolated island microgrid secondary control method based on proportional segment integration includes the following steps:

[0164] S1. Briefly analyze the primary control and secondary control of the microgrid and clarify the control objectives;

[0165] S11. Primary control usually works through a droop controller to maintain voltage and frequency stability; the droop controller of the i-th DG is as follows:

[0166]

[0167] Where P i and Q i is the low-pass filter value of the output active power and reactive power; m Pi and n Qi Respectively represent the active and reactive droop coefficients; ω ni and v ni It is the reference value in the primary control to be designed in the secondary control layer;

[0168] Secondary control includes frequency and voltage secondary control; the purpose of secondary control is to design the control input ω ni and v ni , so that the frequency ω i and the output voltage amplitude v oi.mag Synchronize to nominal value ω ref and v ref , while achieving accurate active power sharing m P1 P1=m P2 P2=…=m PN P N ; Therefore, the objective of the secondary control can be written as:

[0169]

[0170] S2. Establish a large signal dynamic model of distributed generators;

[0171] S21. Typical inverter-based DG structure in island mode is shown in the attached figure. Figure 2 As shown; it contains a DC power source (such as a fuel cell or a solar cell), a voltage source converter (VSC), an LC filter, a load, a transmission line, an output connector and a control loop, which includes a power supply, a voltage and a current controller, and uses a simple PI controller to adjust the output frequency and voltage of the VSC; the nonlinear dynamics of each DG can be expressed in a synchronously rotating dq reference frame; it is assumed that a DG reference frame is taken as a common reference frame, and its rotation angular frequency is ω com , and the reference frame rotation frequency of the i-th DG is ω i ; Due to the frequency droop characteristic of the droop controller, all other reference frames rotate synchronously at a common frequency; e.g. Figure 2 As shown, the nonlinear state space equation of the i-th DG in the dq coordinate system can be expressed as:

[0172]

[0173] Where, L fi , R fi , C fi are the inductance, resistance and capacitance of the LC filter, L ci , R ci is the inductance and resistance of the output connector; ω ci is the cutoff frequency of the pass filter; δ i represents the angle of the i-th DG reference system relative to the public reference system; i ldi 、i lqi 、v odi 、v oqi 、i odi 、i oqi 、v bdi 、v bqi Respectively represent i li 、v oi 、i oi 、v bi The d-axis component and q-axis component of the output voltage oi.mag should be aligned with the d-axis of the corresponding reference frame, so

[0174] S22. The above large signal dynamics model can be written as follows:

[0175]

[0176] where x i =[δ i , P i , Q i ,i ldi , v odi , v oqi ,i odi ,i oqi ] T ,u i =[u i1 ,u i2 ] T =[v ni ,ω ni ] T ,y i =[y i1 ,y i2 ] T =[v odi ,ω i ] T Represents state, input and output respectively, D i =[ω com , v bdi , v bqi ] T Considered to be a known interference;

[0177] S3, the nonlinear system of the microgrid is transformed into a linearized system using the input-output feedback linearization method, and a proportional fragment integral (PFI) control protocol similar to PI control is designed to eliminate the voltage deviation with multiplicative noise in the communication layer;

[0178] S31. Construct a multi-DG network topology model containing N+1 DGs, where "0" represents the leader and "1, 2, ..., N" represent N followers respectively; assuming that the directed graph is time-invariant, the communication topology between followers is expressed as Likewise, the communication between the leader and followers is defined as Hypothesis Diagram contains a spanning tree, and is an undirected graph;

[0179] S32. It is easy to know from graph theory knowledge is symmetrical, where is the Laplace matrix representing the communication relationship between followers. When DGi is connected to DGj (i≠j), otherwise, (a ij is an element in the adjacency matrix, a ij is not equal to 0, it means that there is information flow from j to i, otherwise, a ij equal to 0); the elements on the diagonal Indicates the connection relationship between the follower and the leader. When DGi is directly connected to the leader, a i0 =1; otherwise, a i0 =0;

[0180] S33, use λ 0i express Therefore, there exists an identity matrix Φ such that And 0<λ 01 ≤…≤λ 0N ;

[0181] S34. For the dynamics of the i-th DG, the nonlinear system can be converted into a linear system using input-output feedback linearization: Among them, F i =f i (x i )+k i (x i )D i ; Define auxiliary control The control input can be obtained as:

[0182]

[0183] Therefore, the dynamic equation of the follower can be expressed as follows:

[0184]

[0185] in B=[0 1] T , it is easy to see that (A, B) is controllable, λ(A) = 0; at the same time, the leader's dynamic equation can be described as:

[0186]

[0187] in

[0188] S35. Design the distributed voltage proportional fragment integration (PFI) control protocol as follows:

[0189]

[0190] where k p1 , k p2 is the feedback gain of the proportional term to be designed, k i1 , k i2 is the feedback gain of the integral term to be designed. It should be noted that it contains segment integral (distributed delay) with segment length h>0, which is different from the integral term in PI control;

[0191] where z 1ji (t) = y j1 (t)-y i1 (t)+f 1ji (y j1 (t)-y i1 (t))ξ 1ji (t), z 2ji (t) = y j1，2 (t)-y i1，2 (t)+f 2ji (y j1，2 (t)-y i1，2 (t))ξ 2ji (t), is the voltage measured by the i-th DG from its neighbor j-th DG and the derivative of the voltage; ξ 1ji (t), ξ 2ji (t) is the measurement noise, which is assumed to be scalar-independent Gaussian white noise, and satisfy Among them, {w ji (t), i=1, 2,..., N, j∈N i}, is defined in the complete probability space Independent two-dimensional Brownian motion on 1ji (·), f 2ji(·) is the noise intensity function and satisfies that for each (j, i), f 1ji (0) = f 2ji (0)=0, and there exists a non-negative constant So that for all have

[0192] S4. According to the control protocol, the voltage consistency problem in the multiplicative noise environment is transformed into the stability problem of the stochastic differential equation;

[0193] S41. Definition:

[0194]

[0195] δ1(t)=[δ 11 (t),…,δ 1N (t)] T ,δ2(t)=[δ 1，21 (t),…,δ 1，2N (t)] T ,

[0196]

[0197] S42. Using protocol (8) and making some transformations, the closed-loop system can be expressed as:

[0198]

[0199] in M 12 (t)=M1(t)+M2(t), M 34 (t) = M3(t) + M4(t), we can get:

[0200]

[0201] Among them, B 1ji (t) = [0 b 1ji (t) T ] T , B 2ji (t) = [0 b 2ji (t) T ] T , b 1ji (t)=Φ(i)f 1ji (δ 1j (t)-δ 1i (t)), b 2ji (t)=Φ(i)f 2ji (δ 1，2j (t)-δ 1，2i (t));

[0202] S5. Construct the mean square consistent stability criterion and the almost certain consistent stability criterion about the controller parameters, and the feasibility conditions for achieving voltage synchronization;

[0203] S51, Order Then (9) can be written as:

[0204]

[0205] make Consider the Lyapunov candidate function V1 = z(t) T Pz(t); Applying Ito's formula gives:

[0206]

[0207] S52. Using elementary inequalities: (O positive definite, ε>0) and Lemma (P positive definite, h>0), we can get:

[0208]

[0209]

[0210] Substituting the above three inequalities into (10), we can obtain:

[0211]

[0212] in

[0213] S53. Consider another additional Lyapunov candidate function Differentiating it gives:

[0214]

[0215] Selecting the Lyapunov functional V(t)=V1(t)+V2(t), we can get:

[0216]

[0217] in

[0218] S54. Select a positive definite matrix μ, θ>0 are the parameters to be designed; using the square sum property of the undirected graph: We can get: and therefore:

[0219]

[0220] in From the above, we can see that formula (13) can be expressed as:

[0221] Where S3=S2+U1,dM 12 =2z(t) T PdM 12 ;

[0222] S55, for e γt V(t) uses Ito's formula, then for any γ>0, we have:

[0223]

[0224] Integrating both sides of the above inequality and then finding the expectation gives:

[0225]

[0226] S56. From the definition of Lyapunov functional V(t) and elementary inequalities, we know that: as well as So we can get:

[0227]

[0228] At the same time, we know that:

[0229]

[0230] in

[0231] S57, because So considering that we can first find

[0232]

[0233] Apply the formula Can get

[0234]

[0235] Through similar derivation as before, we can conclude that:

[0236]

[0237] Therefore, we can get:

[0238]

[0239] in Similarly, we can get:

[0240]

[0241] S58. Substituting equations (19) and (21) into (17), we can obtain:

[0242]

[0243] in

[0244] C3(γ)=γ(2||P||+C1he γh ), S4(γ)=S1+C3(γ)I n +C4(γ)U2, it is easy to see that C3(0)=0,

[0245] S59. In summary, it can be deduced that if the conditions are met:

[0246]

[0247] Then S4(0)<0, so there must be a constant γ * > 0, so that for any γ < γ * , S4(γ)<0, and then add formula (22) to get: Therefore, it can be concluded and

[0248] S6, selecting appropriate PFI control gains for the proposed stability criteria and feasibility conditions to achieve voltage synchronization of each DG to the reference value;

[0249] S61. According to the proposed stability criterion (23), it is necessary to choose Let k1 = k p1 +hk i1 , k2=k p2 +hk i2 , and using the inequality:

[0250]

[0251] You can get: in and At the same time, note that At the same time, select ε1=ε2=h 2 , So we can get:

[0252]

[0253] in

[0254]

[0255]

[0256] S62, need to let S 11 (θ)<0,S 22 (θ)<0, and it can be deduced that θ>θ1 means S 11 (θ)<0, and θ<θ2 means S 22 (θ)<0. Where:

[0257]

[0258] Note that it is necessary to ensure that θ1 < θ2, then for any θ∈(θ1, θ2), there is S 11 (θ)<0,S 22 (θ)<0;

[0259] S62. In fact, we need θ 2 <μλ 01 To ensure the positive definiteness of P, since we have chosen Therefore, it is necessary to meet: It can be solved when 0<θ<θ * This condition can be satisfied when By comparison, we can conclude that θ2<θ * , so it can be concluded that for any θ∈(θ1,θ2), it can be guaranteed that P>0, S<0;

[0260] S63, in summary, here we select θ=1, k p1 =3, k i1 =5, k p2 =10, k i2 =15, h=0.01, The above conditions can be met to achieve synchronous voltage recovery to the reference value;

[0261] S7, use the same method as above to perform PFI secondary control on the frequency, so as to synchronize the frequency of each DG to the reference value while maintaining reasonable active power sharing;

[0262] S71. Similar to the above method, the proportional fragment integral (PFI) control protocol that introduces multiplicative noise in the communication layer is also considered. First, the droop control is feedback linearized: And use the following control protocol:

[0263]

[0264] where z ωji (t) = ω j (t)-ω i (t)+f ωji (ω j (t)-ω i (t))ξ ωji (t), at the same time, it is also necessary to ensure reasonable power sharing: However, frequency control alone may lead to inaccurate active power sharing; therefore, in order to achieve accurate power sharing, active power auxiliary control is considered: Also design the control protocol:

[0265]

[0266] where z Pji (t) = m Pj P j (t)-m Pi P i (t)+f Pji (m Pj P j (t)-m Pi P i (t))ξ Pji (t), therefore, the noise-resistant protocol for frequency recovery and active power sharing accuracy in secondary control can be written as:

[0267] ω ni =∫(u ωi +u Pi )dt (27)

[0268] In the same way, it can be concluded that the condition for frequency synchronization to the reference value is that there are constants ε1, ε2, ε3>0:

[0269]

[0270] as well as

[0271]

[0272] S72. In summary, we can choose k ωp =3, k ωi =5, k Pp =3, k Pi =5, h=0.01, The above conditions can be met to achieve frequency synchronization recovery to the reference value and accurate sharing of active power.

[0273] In order to verify the effectiveness of this embodiment, a MATLAB simulation experiment was carried out to simulate the distributed coordinated control of a microgrid with four distributed generators. The communication topology relationship is shown in the attached figure. Figure 3 As shown; at 1 second, the microgrid applies secondary control. The specific microgrid structure is shown in the attached figure. Figure 4 As shown; attached Figure 5 The output voltage amplitude of all distributed generators in the group changes, and finally tends to the expected value of 380V. Figure 6 The output frequency changes of all distributed generators are shown, and finally they tend to the expected value of 50Hz. Figure 7 The accurate distribution of the output active power of all distributed generators is represented, and the simulation results demonstrate the reliability of the theoretical derivation.

[0274] The present invention provides an isolated microgrid distributed secondary control method based on a proportional fragment integral (PFI) control protocol in a multiplicative measurement noise environment for a microgrid system including multiple distributed generators, belonging to the field of smart grid control; each distributed generator uses its own information and the information of other distributed generators that can exchange information with it to construct a reasonable corresponding PFI distributed control protocol, so that the output voltage amplitude and frequency of all distributed generators track the leader reference value, and at the same time, reasonable active power distribution is achieved; the present invention takes into account the multiplicative measurement noise in the information transmission of the secondary control communication layer, realizes coordinated control between distributed generators, restores the voltage and frequency to the reference value, compensates for the deviation of the primary control, and thus ensures the stability of the smart microgrid.

[0275] This embodiment provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the above-mentioned isolated microgrid secondary control method based on proportional segment integration are implemented. Among them, the storage medium can be a disk, an optical disk, a read-only memory (ROM), a random access memory (RAM), a flash memory, a hard disk drive (HDD) or a solid-state drive (SSD), etc.; the storage medium can also include a combination of the above-mentioned types of memory.

[0276] This embodiment provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the steps of the above-mentioned isolated island microgrid secondary control method based on proportional segment integration are implemented.

[0277] like Figure 8As shown, the computer device may include: at least one processor 121, such as a CPU (Central Processing Unit), at least one communication interface 123, a memory 124, and at least one communication bus 122. Among them, the communication bus 122 is used to realize the connection and communication between these components. Among them, the communication interface 123 may include a display screen (Display), a keyboard (Keyboard), and the optional communication interface 123 may also include a standard wired interface and a wireless interface. The memory 124 may be a high-speed RAM memory (Random Access Memory, volatile random access memory) or a non-volatile memory (non-volatile memory), such as at least one disk memory. The memory 124 may also be at least one storage device located away from the aforementioned processor 121. Among them, the memory 124 stores an application program, and the processor 121 calls the program code stored in the memory 124 to perform any of the above method steps. Among them, the communication bus 122 may be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus, etc. The communication bus 122 can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 8Only one line is used to represent it, but it does not mean that there is only one bus or one type of bus. Among them, the memory 124 may include a volatile memory (English: volatile memory), such as a random access memory (English: random-access memory, abbreviated: RAM); the memory may also include a non-volatile memory (English: non-volatile memory), such as a flash memory (English: flash memory), a hard disk drive (English: hard disk drive, abbreviated: HDD) or a solid-state drive (English: solid-state drive, abbreviated: SSD); the memory 124 may also include a combination of the above-mentioned types of memory. Among them, the processor 121 may be a central processing unit (English: central processing unit, abbreviated: CPU), a network processor (English: network processor, abbreviated: NP) or a combination of CPU and NP. Among them, the processor 121 may further include a hardware chip. The above-mentioned hardware chip may be an application-specific integrated circuit (English: application-specific integrated circuit, abbreviated: ASIC), a programmable logic device (English: programmable logic device, abbreviated: PLD) or a combination thereof. The PLD can be a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), a generic array logic (GAL), or any combination thereof. Optionally, the memory 124 is also used to store program instructions. The processor 121 can call the program instructions to implement the isolated island microgrid secondary control method based on proportional segment integration as in this embodiment.

[0278] The specific implementations described above are preferred implementations of the isolated microgrid secondary control method, medium and device based on proportional segment integration of the present invention, and are not intended to limit the specific implementation scope of the present invention. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the scope of the present invention includes but is not limited to this specific implementation. Under the premise of not departing from the design spirit of the present invention, various modifications and improvements made to the technical solution of the present invention by ordinary technicians in this field should fall within the protection scope determined by the claims of the present invention.

[0279] It should also be noted that the embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, which are all within the protection of the present invention.

Claims

1. A secondary control method for an island microgrid based on proportional segment integration, characterized in that: The following steps are involved: S1: According to the microgrid to be controlled, a droop controller is set to build a control target; S2: constructing a large signal dynamic model of a distributed generator according to the droop controller and the microgrid to be controlled; S3: According to the large signal dynamic model of the distributed generator, the system linear model is obtained by using the input-output feedback linearization method; according to the system linear model, a proportional-fraction-integral control protocol is constructed; S4: According to the proportional-segment-integral control protocol and the control target, the voltage consistency problem in the multiplicative noise environment is converted into a stability problem of a stochastic differential equation, and a closed-loop system stochastic differential equation is obtained; S5: constructing a controller parameter stability criterion and a feasibility condition according to the closed-loop system stochastic differential equation, wherein the controller parameter stability criterion and the feasibility condition are used to achieve the stability of the closed-loop system stochastic differential equation; S6: Obtaining voltage control parameters according to the controller parameter stability criterion and feasibility condition; S7: According to the droop controller, the control target and the microgrid to be controlled, a frequency secondary control protocol and a sufficient condition for the mean square consistency of the output frequency of the distributed generator set are constructed to obtain frequency control parameters.

2. The secondary control method of isolated island microgrid based on proportional segment integration according to claim 1 is characterized in that: Step S1 specifically includes: S11: According to the microgrid to be controlled, a droop controller for the primary control of the microgrid to be controlled is set, such as formula: Among them, ω i is the frequency of the ith generator, ω ni is the reference value in the primary control of the i-th generator to be designed in the secondary control layer, m Pi represents the active power droop coefficient of the i-th generator, P i is the low-pass filtered value of the active power output by the i-th generator, ν oi.mag is the output voltage amplitude of the ith generator, ν ni is the reference value in the primary control of the i-th generator to be designed in the secondary control layer, n Qi represents the reactive power droop coefficient of the i-th generator, Q i is the low-pass filtered value of the reactive power output by the i-th generator; S12: According to the microgrid to be controlled, a control target of the secondary control of the microgrid to be controlled is constructed, such as the formula: Among them, ω i (t) is the frequency of the i-th generator, ω ref is the nominal frequency, m Pi represents the active power droop coefficient of the i-th generator, P i (t) is the low-pass filtered value of the active power output by the ith generator, m Pj represents the active power droop coefficient of the jth generator, P j (t) is the low-pass filtered value of the active power output by the jth generator, v oi.mag (t) is the output voltage amplitude of the ith generator, v ref is the nominal voltage, i and j are the serial numbers of the distributed generators.

3. The secondary control method of isolated island microgrid based on proportional segment integration according to claim 1, characterized in that: Step S2 specifically includes: constructing a large signal dynamic model of a distributed generator according to the droop controller and the microgrid to be controlled, such as the formula: x i =[δ i ,P i ,Q i ,i ldi ,i lqi ,v odi ,v oqi ,i odi ,i oqi ] T , in i =[in i1 ,in i2 ] T =[v ni ,ω ni ] T , and i =[and i1 ,and i2 ] T =[v odi ,ω i ] T , D i =[ω com ,v bdi ,v bqi ] T , g i1 (x i )=v odi ,g i2 (x i )=-m Pi P i ,d i =1, in, is the time derivative of the state of the ith generator, x i is the state of the i-th generator, δ i is the angle of the i-th distributed generation reference system relative to the common reference system, P i is the low-pass filter value of the output active power, Q i is the low-pass filter value of the output reactive power, i ldi and i lqi Respectively represent i li The d-axis component and q-axis component of v odi and v oqi Respectively represent v oi The d-axis component and q-axis component of i odi and i oqi Respectively represent i oi The d-axis component and q-axis component of v bdi and v bqi Respectively represent v bi The d-axis component and q-axis component of i li represents the inverter output current of the ith distributed power source, v oi represents the output voltage of the i-th distributed power source, i oi represents the output current of the i-th distributed power source, v bi represents the bus voltage of the ith distributed generation, D i is the known interference vector, ω com is the frequency interference, f i (x i ), k i (x i ), r i1 (x i ), r i2 (x i ), g i1 (x i ), g i2 (x i ), d i is the intermediate vector, u i is the input vector of the ith generator, u i1 and u i2 is the input of the ith generator, y i is the output vector of the ith generator, y i1 and i2 is the output of the ith generator, ω i is the frequency of the ith generator, ω ni is the reference value in the primary control to be designed in the secondary control layer, m Pi Indicates the active power droop coefficient, v ni is the reference value in the primary control to be designed in the secondary control layer, ω ci is the cutoff frequency of the low-pass filter, L fi , R fi , C fi are the inductance, resistance and capacitance of the LC filter, L ci , R ci is the inductance and resistance of the output connector, ω com is the common angular frequency of the distributed power source.

4. The secondary control method of isolated island microgrid based on proportional segment integration according to claim 1, characterized in that: Step S3 specifically includes: S31: According to the large signal dynamics model of the distributed generator, the nonlinear system is transformed using the input-output feedback linearization method to obtain a system linear model, such as the formula: λ(A)=0, F i =f i (x i )+k i (x i )D i , in, is the derivative of the output vector of the ith generator, A and B are constant matrices, v i is the auxiliary input voltage, v odi The derivative of y i1，2 for λ(A) is the eigenvalue of matrix A, y0 is the leader output, is the derivative of y0, v ref is the nominal voltage, v ref The derivative of ni is the control input voltage, Represents r i1 The Li derivative of Representatives of F i The Li derivative of for y i1 The second derivative of i F i =f i (x i )+k i (x i )D i ; S32: According to the system linear model, a proportional segment integral control protocol is constructed, such as the formula: z 1ji (t)=y j1 (t)-y i1 (t)+f 1ji (y j1 (t)-y i1 (t))ξ 1ji (t) z 2ji (t)=y j1，2 (t)-y i1，2 (t)+f 2ji (y j1，2 (t)-y i1，2 (t))ξ 2ji (t) Among them, v i (t) is the auxiliary input voltage, k p1 , k p2 is the proportional feedback gain to be designed, N i is the neighbor of the ith generator, z 1ji is the voltage measured by the i-th DG from its neighbor j-th DG, k i1 , k i2 is the integral feedback gain to be designed, h is the length of the segment integral, z 2ji is the derivative of the voltage measured by the ith DG from its neighbor, the jth DG.

5. The secondary control method of isolated island microgrid based on proportional segment integration according to claim 1, characterized in that: Step S4 specifically includes: according to the proportional segment integral control protocol and the control target, converting the voltage consistency problem in the multiplicative noise environment into a stability problem of the stochastic differential equation, and obtaining the closed-loop system stochastic differential equation, such as formula: in, M 12 (t)=M1(t)+M2(t), M 34 (t)=M3(t)+M4(t), δ1(t)=[δ 11 (t),…,d 1N (t)] T ,δ2(t)=[δ 1，21 (t),…,d 1，2N (t)] T , B 1ji (t)=[0 b 1ji (t) T ] T ,B 2ji (t)=[0 b 2ji (t) T ] T , b 1ji (t)=Φ(i)f 1ji (d 1j (t)-d 1i (t)), b 2ji (t)=Φ(i)f 2ji (d 1，2j (t)-d 1，2i (t)), in, is the system error vector, for The differential of , h is the length of the fragment integral, the intermediate variable in the calculation process of A1 and A2, is the error vector of the system during the integration time, Λ0 is Λ0=diag(λ 01 , ..., λ 0N ), λ 0i represents the Laplacian matrix The characteristic value of I N is the N-order unit matrix, M 12 (t), M 34 (t), M1(t), M2(t), M3(t), and M4(t) are all random differential equation noise terms, N is the number of followers, and a ij is an element in the adjacency matrix, a ij is not equal to 0, it means that there is information flow from j to i, otherwise, a ij =0; B 1ji (t), B 2ji (t), b 1ji (t) and b 2ji (t) are: B 1ji (t) = [0b 1ji (t) T ] T , B 2ji (t) = [0 b 2ji (t) T ] T , b 1ji (t)=Φ(i)f 1ji (δ 1j (t)-δ 1i (t)), b 2ji (t)=Φ(i)f 2ji (δ 1，2j (t)-δ 1，2i (t)), B 1ji (s) and B 2ji (s) are B in the integral time 1ji (t) and B 2ji (t), w 1ji (s) and w 2ji (s) are defined in the complete probability space Independent two-dimensional Brownian motion on, Φ(i) is Φ(i)=Φ T η N，i , η N，i represents an N-order column vector, the i-th element is 1 and the rest are all 0, Φ is an orthogonal matrix, δ 1i (t) is δ 1i (t) = y 1i (t)-y 10 (t), y 1i (t) is v odi ,y 10 (t) is the leader's v odi , δ 1，2i (t) is y 1，2i (t) is v odi The time derivative, v for leaders odi The time derivatives, δ1(t) and δ2(t), are δ1(t)=[δ 11 (t),…,δ 1N (t)] T ,δ2(t)=[δ 1，21 (t),…,δ 1，2N (t)] T , for g=1 or 2, Φ T is the transpose of the matrix Φ, and are the transpose of the corresponding matrices, f 1ji (.) and f 2ji (.) is the noise intensity function; δ 1j (t) Same meaning as δ 1i (t), the difference is the sequence number; δ 1，2j (t) Same meaning as δ 1.2i (t), the difference is the sequence number.

6. The secondary control method of isolated island microgrid based on proportional segment integration according to claim 1, characterized in that: Step S5 specifically includes: constructing a controller parameter stability criterion and a feasibility condition according to the closed-loop system stochastic differential equation, wherein the controller parameter stability criterion and the feasibility condition are used to achieve the stability of the closed-loop system stochastic differential equation, such as the formula: in, is the matrix A h The transpose of A h is the intermediate variable in the calculation process, P is a positive definite matrix, ε1, ε2 and ε3 are constants, h is the length of the fragment integral, is the transpose of matrix A2, A2 is U1 is U2 is Λ0 is Λ0=diag(λ 01 , ..., λ 0N ), I N is the N-order unit matrix, μ and θ are the parameters to be designed, and is the maximum value of the noise intensity.

7. The secondary control method of isolated island microgrid based on proportional segment integration according to claim 1, characterized in that: Step S7 specifically includes: S71: constructing a frequency secondary control protocol according to the droop controller, the control target and the microgrid to be controlled; S72: According to the frequency secondary control protocol, a sufficient condition for mean square consistency of output frequencies of distributed generator sets is obtained; S73: Obtain frequency control parameters according to the sufficient condition for the mean square consistency of the output frequency of the distributed generator set.

8. The secondary control method of isolated island microgrid based on proportional segment integration according to claim 7 is characterized in that: Step S71 specifically includes: constructing a frequency secondary control protocol according to the droop controller, the control target and the microgrid to be controlled, such as formula: ω ni =∫(u ωi +u Pi )dt, Among them, u ωi (t) is the input of frequency control, k ωp , k ωi are the proportional term and integral term feedback gains to be designed in the frequency control protocol, N i is the neighbor of the i-th distributed generation, z ωji (t) and z ωji (s) is the frequency measured by the ith distributed generator from its neighboring jth distributed generator, u Pi (t) is the input of power control, k Pp , k Pi are the proportional term and integral term feedback gains to be designed in the power control protocol, respectively, Pji (t) and z Pji (s) is the power measured by the i-th distributed generator from its neighbor j-th distributed generator, ω ni ω is the frequency control ni is the reference value in the primary control of the i-th generator to be designed at the secondary control level; Step S72 specifically includes: according to the frequency secondary control protocol, obtaining the sufficient condition for the mean square consistency of the output frequency of the distributed generator set, such as the formula: Among them, ε1, ε2 and ε3 are constants, are the maximum values ​​of noise intensity.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of any of the proportional segment integration-based isolated island microgrid secondary control methods as described in claims 1-8 are implemented.

10. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps of any one of the isolated island microgrid secondary control methods based on proportional segment integration as described in claims 1-8 are implemented.

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