Adaptive control method for precise distribution of reactive power by multi-machine network type converter

Abstract

The application discloses a kind of self-adaptive control methods for accurately distributing reactive power of multiple grid-connected converters, and belongs to the field of parallel control of multiple grid-connected converters.The method obtains the reference value of output voltage phase angle by using active loop control of virtual synchronous generator; the d-q axis voltage component command value is obtained by virtual synchronous generator reactive power loop control and optimization distribution algorithm, and then the modulation wave required for PWM control is obtained by voltage and current double closed loop control, to output switch tube driving signal to complete the control of the converter.Under the premise of not obtaining line impedance information, the application accurately compensates voltage drop by self-adaptive control method, reduces reactive power distribution error, realizes accurate distribution of reactive power according to rated capacity, and improves system stability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of parallel control of multiple grid-forming converters, and particularly relates to an adaptive control method for precise reactive power distribution of multiple grid-forming converters. BACKGROUND

[0002] Common grid-forming converter control technologies include droop control technology, virtual synchronous generator control technology, etc. The virtual synchronous generator technology simulates the rotor inertia, damping characteristics and droop external characteristics of a synchronous generator, so that the inverter has the same steady-state and dynamic characteristics as a synchronous generator, provides damping and inertia support for the system during operation, thereby improving system stability. However, when a system composed of multiple grid-forming converters operates in island mode, due to the random distribution of the geographical positions of the converters, there are differences in the line impedance from the converters to the PCC point, so the system has the problem that the actual output reactive power is difficult to match the rated capacity, and reasonable reactive power distribution cannot be achieved.

[0003] At present, many scholars at home and abroad have proposed various improvement methods for the problem of reasonable reactive power distribution, including line impedance parameter identification method, adaptive virtual impedance method, etc., which obtain the corresponding information to reasonably compensate the voltage drop and achieve reasonable distribution of reactive power, thereby improving system stability. For example:

[0004] 1. In the article titled "Distributed Control Strategy Based on Line Impedance Identification for Reactive Power Sharing in Microgrid, 《2023IEEE Energy Conversion Congress and Exposition (ECCE)》, 2023, 1160-1167, the line parameter values are accurately observed by an observer, then the line voltage drop of each converter is calculated using the observed line parameters, and the reasonable distribution of reactive power of the system is achieved by accurately compensating the voltage. However, the line parameter identification scheme has high requirements for system communication and data measurement accuracy, and is difficult to apply to actual engineering.

[0005] 2. The article titled "Improved Droop Control Strategy for Reactive Power Sharing of Inverters in Low Voltage Microgrid" by Bai Xiaodan, Miao Hong, Zeng Chengbi, and Mostafa in High Voltage Technology, Vol. 46, No. 04, 2020, pp. 1310-1318, collects information from each converter through a central controller for calculation to reasonably design the dynamic virtual impedance part of the adaptive virtual impedance, compensates for the voltage drop caused by the difference in line impedance, and thus reasonably allocates reactive power. However, the centralized control method using a central controller has high requirements for communication quality, and inaccurate information collection may occur due to communication interruption or delay, so the virtual impedance parameters cannot be accurately adapted to the system.

[0006] 3. The article titled "Research on Reactive Power Distribution of Islanded AC Microgrid Based on Improved Droop Control" by Yan Li, Mi Yang, Sun Wei, Cai Hangyi, Niu Qingsong, and Qi Fujun in Solar Energy, Vol. 42, No. 08, 2021, pp. 07-15, collects reactive power information from adjacent converters, obtains the required parameters for constructing an adaptive virtual impedance algorithm through a consistency algorithm, and realizes reasonable reactive power distribution while reducing dependence on global communication. However, it is only applicable to the case where the capacities of each converter are equal, and when the capacities are not equal, the reactive power cannot be reasonably allocated in proportion to the capacity.

[0007] In summary, existing research mainly focuses on parameter identification methods and adaptive virtual impedance methods, and the following technical problems still exist:

[0008] 1. The identification effect requires high data measurement accuracy, which is difficult to apply in practical engineering;

[0009] 2. Large virtual impedance will lead to reduced system voltage control accuracy and affect the dynamic characteristics of the system output voltage;

[0010] 3. The system has high requirements for communication quality and relies too much on global communication, and fluctuations in communication quality will lead to differences in control effect;

[0011] 4. The system has the limitation that the capacities of each converter are equal, and when the capacities are not equal, the target control effect cannot be achieved. SUMMARY

[0012] The technical problem to be solved by the present application is the accurate allocation of reactive power of each converter in the case of multiple grid-connected converters based on virtual synchronous generator technology connected to the load. The present application provides an adaptive control method for accurately allocating reactive power of multiple grid-connected converters to enable each converter to accurately share reactive load and ensure stable operation of the system.

[0013] The technical solution of the present application is as follows.

[0014] The application discloses an adaptive control method for accurately distributing reactive power of a plurality of grid-connected converters, and relates to a system composed of X grid-connected converters based on virtual synchronous generator technology, wherein each grid-connected converter is connected to a load in parallel, any one of the grid-connected converters is recorded as grid-connected converter i (i belongs to [1, X]), Y grid-connected converters adjacent to the grid-connected converter i are recorded as adjacent grid-connected converter j (j belongs to [1, Y]), Y is less than X, and a distributed communication network of the X grid-connected converters is constructed in the system, specifically, the grid-connected converter i can send information to the adjacent grid-connected converter j and receive information sent by the adjacent grid-connected converter j.

[0015] The adaptive control method comprises the following steps.

[0016] Step 1: sampling three-phase output voltages u ai ,u bi ,u ci and three-phase output currents i ai ,i bi ,i ci of the grid-connected converter i, performing coordinate transformation to obtain dq-axis output voltage components U di ,U qi and dq-axis output current components I di ,I qi in a synchronous rotating coordinate system, and then calculating output active power P ei and output reactive power Q ei of the grid-connected converter i through power calculation.

[0017] Step 2: performing virtual synchronous generator control according to the output active power P ei and the output reactive power Q ei of the grid-connected converter i, specifically, obtaining an output voltage angular frequency reference value ω i through an active ring control equation, obtaining an output voltage phase angle reference value θ i , and θ i = ∫ω i , and obtaining a voltage reference value U ni through a reactive ring control equation given a reactive-voltage droop coefficient k refi .

[0018] Step 3: the grid-connected converter i obtains output reactive power Q ej and a reactive-voltage droop coefficient k nj of the adjacent grid-connected converter j through communication, and combines the output reactive power Q ei and the reactive-voltage droop coefficient k ni of the grid-connected converter i.The virtual capacitance droop coefficient compensation value Δn is obtained through a multi-agent consensus algorithm. ci With virtual inductance compensation value ΔL vi ;

[0019] Step 4, based on the voltage reference value U refi And virtual capacitance droop coefficient compensation value Δn ci The standard value component U of the virtual voltage along the d-axis is calculated using a virtual capacitance algorithm. rdi ; The q-axis virtual voltage standard value component U rqi Set it to 0, and then calculate the virtual voltage standard value component U along the d-axis. rdi and virtual inductance compensation value ΔL vi The command value U of the dq axis voltage component is calculated using a virtual inductance algorithm. clrdi U clrqi ;

[0020] Step 5, based on the dq axis voltage component command value U clrdi U clrqi and the output voltage phase angle reference value θ i A dual closed-loop control of voltage and current is implemented for grid-type converter i. Specifically, the output I of the outer loop control of the dq-axis output voltage is calculated using the outer loop control equation of the dq-axis output voltage. rdi ,I rqi Then, the output U of the dq-axis output current inner loop control is obtained through the dq-axis output current inner loop control equation. pdi U pqi Then, the three-phase modulated wave signal u is obtained through coordinate transformation. pai ,u pbi ,u pci And generate the switching drive signal for the grid-type converter i.

[0021] Preferably, the output active power P of the grid-type converter i in step 1 is... ei and output reactive power Q ei The calculation formulas are as follows:

[0022]

[0023] Preferably, the active power loop control equation in step 2 is:

[0024]

[0025] Where, ω 0i ω is the rated angular frequency of the system voltage. i ′ represents the reference value of the output voltage angular frequency in the previous control cycle, k ωi P is the primary frequency modulation coefficient. refi J is the active power command value. ivirtual inertia;

[0026] The reactive loop control equation is:

[0027] U refi =U 0i -k ni (Q ei -Q refi )

[0028] wherein U 0i is a system rated output voltage amplitude, Q refi is a reactive power command value.

[0029] Preferably, the expression of the multi-agent consensus algorithm in step 3 is:

[0030]

[0031] wherein C Qi is a control gain, a ij is a weight coefficient set according to whether the network-forming converter i can communicate with the adjacent network-forming converter j, a ij =1 if communication is possible, and a ij =0 if communication is not possible, k pyi is a proportional coefficient in the multi-agent consensus algorithm, k iyi is an integral coefficient of the multi-agent consensus algorithm, and s is a Laplace operator.

[0032] Preferably, the calculation formula of the d-axis virtual voltage component standard value U rdi in step 4 is:

[0033]

[0034] wherein U maxi is a maximum voltage amplitude allowed by the system, Q ratei is a rated reactive power of the network-forming converter i, n rci is a virtual capacitor droop coefficient fixed value, and K Qci is a virtual capacitor proportional gain.

[0035] The calculation formula of the dq-axis voltage component command value U clrdi , U clrqi is:

[0036]

[0037] wherein ω 0i is a rated angular frequency of the system voltage, L rvi is a virtual inductance fixed value, and K Qli is a virtual inductance proportional gain.

[0038] Preferably, the dq-axis output voltage outer loop control equation in step 5 is:

[0039]

[0040] In the formula, k spvi is the proportional coefficient of the output voltage outer loop proportional-integral controller, k sivi is the integral coefficient of the output voltage outer loop proportional-integral controller, and s is the Laplace operator;

[0041] The dq-axis output current inner loop control equation is:

[0042]

[0043] In the formula, k spii is the proportional coefficient of the output current inner loop proportional-integral controller, k siii is the integral coefficient of the output current inner loop proportional-integral controller.

[0044] The adaptive control method for precisely distributing reactive power of multiple network-forming converters disclosed in the application has the following beneficial effects compared with the existing reactive power distribution schemes based on line impedance identification and the reactive power distribution schemes based on adaptive virtual impedance algorithms:

[0045] 1. The adaptive control method adds virtual capacitor algorithm and virtual inductor algorithm to compensate for system voltage drop in the conventional network-forming converter control based on virtual synchronous generator technology, and realizes reactive power distribution according to the rated capacity of the system.

[0046] 2. The adaptive control method uses multi-agent consistency algorithm for adaptive control of the virtual capacitor algorithm and the virtual inductor algorithm, obtains the algorithm parameters of the matching system without obtaining any line impedance information, only obtains the reactive power-voltage droop coefficient and reactive power information of the adjacent network-forming converter, and has simple and accurate and reliable parameter design method, which is beneficial to engineering application.

[0047] 3. The adaptive control method can reduce the dependence on global communication, and the reactive power distribution effect is not affected by communication delay and load mutation, and has high reliability when responding to environmental and system changes. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 Fig. 3 is a control structure diagram of X network-forming converters connected in parallel to a load in the application.

[0049] Figure 2 Fig. 4 is a network-forming converter control structure diagram based on adaptive control in the embodiment of the application.

[0050] Figure 3For the embodiment of the present application, the output reactive power Q of the two grid-connected converter parallel system without introducing the virtual capacitance algorithm and the virtual inductance algorithm e1 , e2 The waveform diagram and the output reactive power distribution error Q error Waveform diagram, Qerror=(Qrate2Qe1-Qrate1Qe2) / Qload.

[0051] Figure 4 For the embodiment of the present application, the output reactive power Q of the two grid-connected converter parallel system without introducing the virtual capacitance algorithm and the virtual inductance algorithm e1 , e2 The waveform diagram and the output reactive power distribution error Q error Waveform diagram.

[0052] Figure 5 For the embodiment of the present application, the output reactive power Q of the two grid-connected converter parallel system without introducing the virtual capacitance algorithm and the virtual inductance algorithm e1 , e2 The waveform diagram and the output reactive power distribution error Q error Waveform diagram.

[0053] Figure 6 For the embodiment of the present application, the output reactive power Q of the two grid-connected converter parallel system without introducing the virtual capacitance algorithm and the virtual inductance algorithm e1 , e2 The waveform diagram and the output reactive power distribution error Q error Waveform diagram. DETAILED DESCRIPTION

[0054] The embodiment will be specifically described below in combination with the drawings.

[0055] Figure 1 The control structure diagram of X grid-connected converters connected in parallel to the load in the present application is shown in Figure 1 It can be seen that the present application provides an adaptive control method for precisely distributing reactive power of multiple grid-connected converters, which relates to a system composed of X grid-connected converters based on virtual synchronous generator technology, each converter is connected to the load in parallel, and any one of the grid-connected converters is recorded as grid-connected converter i, i∈[1,X]. Let the grid-connected converters adjacent to the grid-connected converter i be Y, and any one of them is recorded as adjacent grid-connected converter j, j∈[1,Y], YX.

[0056] In the system, a distributed communication network of X grid-connected converters is constructed, specifically, the grid-connected converter i can send information to the adjacent grid-connected converter j and receive information sent by the adjacent grid-connected converter j.

[0057] In addition, by Figure 1 It can be seen that between each grid-connected converter and the load, a CL filter and a line impedance are also connected in series. In the figure, L fi is the inductance of the filter, C fi is the capacitance of the filter, L li is the inductance of the line impedance, and r li is the resistance of the line impedance.

[0058] In the embodiment, X = 2 and Y = 1 are selected. That is, there are two grid-connected converters in the system, the DC side voltage DC of the grid-connected converter 1 is 600 V, L fi is 0.5 mH, C fi is 0.09 mF, the inductance L li of the line impedance of the grid-connected converter 2 is 0.65 mH, and the resistance r li of the line impedance is 0.65 Ω. The inductance L li of the line impedance of the grid-connected converter 2 is 0.7 mH, and the resistance r li of the line impedance is 0.7 Ω, and other parameters are the same. The rated capacity Q rate1 of the grid-connected converter 1 is 100 kVA, and the rated capacity Q rate2 of the grid-connected converter 2 is 80 kVA.

[0059] Figure 2 is the control structure diagram of the grid-connected converter based on the adaptive control in the embodiment of the application, which comprises Figure 1 and Figure 2 It can be seen that the adaptive control method comprises the following steps:

[0060] Step 1, sampling the three-phase output voltage u ai , u bi , u ci and the three-phase output current i ai , i bi , i ci of the output end of the grid-connected converter i, performing coordinate transformation to obtain the dq-axis output voltage components U di , U qi and the dq-axis output current components I di , I qi in the synchronous rotating coordinate system, and then calculating the output active power P ei and the output reactive power Q ei of the grid-connected converter i through power calculation..

[0061] In the embodiment, the output active power P ei and the output reactive power Q ei of the network-constructing converter i are calculated according to the following formulas respectively:

[0062]

[0063] Step 2, virtual synchronous generator control is performed according to the output active power P ei and the output reactive power Q ei of the network-constructing converter i. Specifically, the output voltage angular frequency reference value ω i is obtained through an active loop control equation, and the output voltage phase angle reference value θ i is obtained, θ i =∫ω i ; given the reactive power-voltage droop coefficient k ni , the voltage reference value U refi is obtained through a reactive loop control equation.

[0064] In the embodiment, the active loop control equation is as follows:

[0065]

[0066] wherein ω 0i is the rated angular frequency of the system voltage, ω i ' is the output voltage angular frequency reference value of the previous control period, k ωi is the primary frequency modulation coefficient, P refi is the active power instruction value, and J i is the virtual inertia.

[0067] The reactive loop control equation is as follows:

[0068] U refi =U 0i -k ni (Q ei -Q refi )

[0069] wherein U 0i is the rated output voltage amplitude of the system, and Q refi is the reactive power instruction value.

[0070] In the embodiment, ω 0i =314.159 rad / s, k ωi =31831 Ws / rad, P refi =0 kW, J i =1 kgm 2 , U 0i =311 V, and kni = 0.00012 V / kVA, i = 2 ni = 0.00015 V / kVA, Q refi = 0 kVA.

[0071] Step 3, the grid-forming converter i obtains the output reactive power Q of the adjacent grid-forming converter j through communication ej and the reactive-voltage droop coefficient k nj , combines the output reactive power Q of the grid-forming converter i ei and the reactive-voltage droop coefficient k ni , and obtains the virtual capacitance droop coefficient compensation value An ci and the virtual inductance compensation value AL through the multi-agent consensus algorithm vi .

[0072] In this embodiment, the expression of the multi-agent consensus algorithm is:

[0073]

[0074] wherein, C Qi is a control gain, a ij is a weight coefficient set according to whether the grid-forming converter i and the adjacent grid-forming converter j can communicate, a ij = 1 if communication is possible, and a ij = 0 if communication is not possible, k pyi is a proportional coefficient in the multi-agent consensus algorithm, k iyi is an integral coefficient of the multi-agent consensus algorithm, and s is a Laplace operator.

[0075] In this embodiment, k nj = 0.00015 V / kVA when i = 1, and k nj = 0.00012 V / kVA when i = 2. a ij = 1, C Qci = 10, k pyi = 0.005, and k iyi = 1.

[0076] Step 4, the d-axis virtual voltage standard component U refi is calculated through the virtual capacitance algorithm according to the voltage reference U ci and the virtual capacitance droop coefficient compensation value An rdi ; the q-axis virtual voltage standard component U rqi is set to 0, and then the dq-axis voltage component instruction value U rdi is calculated through the virtual inductance algorithm according to the d-axis virtual voltage standard component U vi and the virtual inductance compensation value ALclrdi ,U clrqi .

[0077] In the embodiment, the d-axis virtual voltage component standard value U rdi is calculated by the following formula:

[0078]

[0079] wherein U maxi is the maximum voltage amplitude allowed by the system, Q ratei is the rated reactive power of the grid-forming converter i, n rci is a virtual capacitance droop coefficient fixed value, and K Qci is a virtual capacitance proportional gain.

[0080] The d-q axis voltage component instruction value U clrdi and U clrqi are calculated by the following formula:

[0081]

[0082] wherein ω 0i is the rated angular frequency of the system voltage, L rvi is a virtual inductance fixed value, and K Qli is a virtual inductance proportional gain.

[0083] In the embodiment, when i = 1, U maxi = 231.48 V, n rci = 1 F / kVA, L rvi = 0.65 mH, K Qci = 0.001, and K Qli = 0.001; and when i = 2, n rci = 0.8 F / kVA, L rvi = 0.2 mH, K Qci = 0.001, and K Qli = 0.001.

[0084] Step 5, voltage and current double-loop control of the grid-forming converter i is performed according to the d-q axis voltage component instruction value U clrdi and U clrqi and the output voltage phase angle reference value θ i . Specifically, the d-q axis output voltage outer loop control output I rdi and I rqi are calculated by the d-q axis output voltage outer loop control equation, the d-q axis output current inner loop control output U pdi and U pqi are obtained by the d-q axis output current inner loop control equation, and the three-phase modulation wave signal u pai is obtained by coordinate transformation.pbi ,u pci And generate the switching drive signal for the grid-type converter i.

[0085] In this embodiment, the outer loop control equation for the dq axis output voltage is:

[0086]

[0087] In the formula, k spvi k is the proportional coefficient of the outer loop proportional-integral controller for the output voltage. sivi is the integral coefficient of the outer loop proportional-integral controller for the output voltage, and s is the Laplace operator;

[0088] The inner loop control equation for the dq axis output current is:

[0089]

[0090] Where, k spii k is the proportional coefficient of the inner loop proportional-integral controller for the output current. siii The integral coefficient of the output current inner-loop proportional-integral controller.

[0091] In this embodiment, k spvi =0.6,k sivi =800,k spii =0.8, k siii =0.

[0092] In this embodiment, the invention is applicable to a parallel system of multiple grid-connected converters based on virtual synchronous generator technology, enabling the rational distribution of reactive power output from each grid-connected converter when the system operates in off-grid mode. To demonstrate the technical effectiveness of this invention, [the following is a description of a system using...]. Figure 2 The control method shown was used to simulate a parallel system of two grid-type converters.

[0093] Figure 3 When neither of the two grid-connected converters introduces virtual capacitor or virtual inductor algorithms, the system output reactive power Q is... ei and reactive power distribution error (Q) rate2 Q e1 -Q rate1 Q e2 / Q load The waveform shows that due to the difference in line impedance between the two grid-connected converters and the load, the ratio of the reactive power output of converter 1 and converter 2 is approximately 1.09, which differs from their rated reactive power ratio of 1.25. Furthermore, the reactive power distribution error Q... error The value is approximately -3500Var.

[0094] Figure 4The virtual capacitor algorithm and the virtual inductor algorithm are introduced into the two grid-connected type converters, and adaptive control is performed by using the multi-agent consistency algorithm, so that the system output reactive power Q ei and the reactive power distribution error Q rate2 Q e1 -Q rate1 Q e2 / Q load It can be seen that the ratio of the output reactive power of the converter 1 and the converter 2 is close to 1.25, which is equal to the ratio of the rated reactive power, and the value of the reactive power distribution error Q error is close to 0, realizing accurate distribution of the output reactive power according to the rated capacity. The virtual capacitor algorithm and the virtual inductor algorithm optimized based on the multi-agent consistency algorithm effectively solve the problem that the reactive power cannot be reasonably distributed.

[0095] Figure 5 The virtual capacitor algorithm and the virtual inductor algorithm are introduced into the two grid-connected type converters, and adaptive control is performed by using the multi-agent consistency algorithm, so that when the reactive load suddenly changes from 80kVA to 60kVA at 3s, the system output reactive power Q ei and the reactive power distribution error Q error The waveforms can be seen that the ratio of the output reactive power of the converter 1 and the converter 2 is close to 1.25, which is equal to the ratio of the rated reactive power, and the value of the reactive power distribution error Q error is close to 0, realizing accurate distribution of the output reactive power according to the rated capacity. The optimization distribution effect is not affected by the load change.

[0096] Figure 6 The virtual capacitor algorithm and the virtual inductor algorithm are introduced into the two grid-connected type converters, and adaptive control is performed by using the multi-agent consistency algorithm, so that when the system communication has a 30ms delay, the system output reactive power Q ei and the reactive power distribution error Q error The waveforms can be seen that the ratio of the output reactive power of the converter 1 and the converter 2 is close to 1.25, which is equal to the ratio of the rated reactive power, and the value of the reactive power distribution error Q error is close to 0, realizing accurate distribution of the output reactive power according to the rated capacity. The optimization distribution effect is not affected by the communication delay.

Claims

1. An adaptive control method for precise reactive power distribution among multiple grid-connected converters, characterized in that, The adaptive control method involves a system consisting of X grid-type converters based on virtual synchronous generator technology. Each converter is connected to the load in parallel. Any one of these grid-type converters is denoted as grid-type converter i, where i ∈ [1, X]. There are Y grid-type converters adjacent to grid-type converter i, and any one of them is denoted as adjacent grid-type converter j, where j ∈ [1, Y], and Y < X. A distributed communication network of X grid-type converters is constructed in the system. Specifically, grid-type converter i can send information to adjacent grid-type converter j and receive information sent by adjacent grid-type converter j. The adaptive control method includes the following steps: Step 1: Sample the three-phase output voltage u at the output terminal of the grid-type converter i. ai ,u bi ,u ci and three-phase output current i ai i bi i ci After coordinate transformation, the dq-axis output voltage component U in the synchronous rotating coordinate system is obtained. di U qi and dq axis output current component I di ,I qi Then, the output active power P of the grid-type converter i is obtained through power calculation. ei With output reactive power Q ei ; Step 2, based on the output active power P of the grid-type converter i ei With output reactive power Q ei Virtual synchronous generator control is implemented, specifically by obtaining the output voltage angular frequency reference value ω through the active power loop control equation. i And obtain the output voltage phase angle reference value θ i , ; Given the reactive power-voltage droop factor k ni The voltage reference value U is obtained through the reactive power loop control equation. refi ; Step 3: Grid converter i obtains the output reactive power Q of the adjacent grid converter j through communication. ej With reactive power-voltage droop coefficient k nj Combined with the output reactive power Q of the grid-type converter i ei and reactive power-voltage droop coefficient k ni The virtual capacitance droop coefficient compensation value Δn is obtained through a multi-agent consensus algorithm. ci With virtual inductance compensation value ΔL vi ; The expression for the multi-agent consensus algorithm is: Among them, C Qi To control the gain, a ij The weighting coefficient is set based on whether grid-type converter i can communicate with its adjacent grid-type converter j. If communication is possible, then a... ij =1, if communication is impossible, then a ij =0,k pyi k is the proportionality coefficient in the multi-agent consensus algorithm. iyi denoted as the integral coefficient of the multi-agent consensus algorithm, and s is the Laplace operator; Step 4, based on the voltage reference value U refi And virtual capacitance droop coefficient compensation value Δn ci The standard value component U of the virtual voltage along the d-axis is calculated using a virtual capacitance algorithm. rdi ; The q-axis virtual voltage standard value component U rqi Set it to 0, and then calculate the virtual voltage standard value component U along the d-axis. rdi and virtual inductance compensation value ΔL vi The command value U of the dq axis voltage component is calculated using a virtual inductance algorithm. clrdi U clrqi ; Step 5, based on the dq axis voltage component command value U clrdi U clrqi and the output voltage phase angle reference value θ i A dual closed-loop control of voltage and current is implemented for grid-type converter i. Specifically, the output I of the outer loop control of the dq-axis output voltage is calculated using the outer loop control equation of the dq-axis output voltage. rdi ,I rqi Then, the output U of the dq-axis output current inner loop control is obtained through the dq-axis output current inner loop control equation. pdi U pqi Then, the three-phase modulated wave signal u is obtained through coordinate transformation. pai ,u pbi ,u pci And generate the switching drive signal for the grid-type converter i.

2. The adaptive control method for precise reactive power distribution of multiple grid-connected converters according to claim 1, characterized in that, The output active power P of the grid-type converter i described in step 1 ei and output reactive power Q ei The calculation formulas are as follows: 。 3. The adaptive control method for precise reactive power distribution of multiple grid-connected converters according to claim 1, characterized in that, The active power loop control equation described in step 2 is: Where, ω 0i The system voltage's rated angular frequency, k is the reference value for the output voltage angular frequency of the previous control cycle. ωi P is the primary frequency modulation coefficient. refi J is the active power command value. i This is virtual inertia; The reactive power loop control equation is as follows: Among them, U 0i Q is the rated output voltage amplitude of the system. refi This is the reactive power command value.

4. The adaptive control method for precise reactive power distribution of multiple grid-connected converters according to claim 1, characterized in that, The standard value U of the d-axis virtual voltage component described in step 4 rdi The formula for calculation is: Among them, U maxi Q is the maximum allowable voltage amplitude of the system. ratei n is the rated reactive power of grid-type converter i. rci K is a fixed value for the virtual capacitance droop factor. Qci This is the virtual capacitance proportional gain; The dq axis voltage component command value U clrdi U clrqi The formula for calculation is: Where, ω 0i L is the rated angular frequency of the system voltage. rvi K is a fixed value for the virtual inductance. Qli This is the gain of the virtual inductor.

5. The adaptive control method for precise reactive power distribution of multiple grid-connected converters according to claim 1, characterized in that, The outer loop control equation for the dq axis output voltage in step 5 is: In the formula, k spvi k is the proportional coefficient of the outer loop proportional-integral controller for the output voltage. sivi is the integral coefficient of the outer loop proportional-integral controller for the output voltage, and s is the Laplace operator; The inner loop control equation for the dq axis output current is: Where, k spii k is the proportional coefficient of the inner loop proportional-integral controller for the output current. siii The integral coefficient of the output current inner-loop proportional-integral controller.

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