CN-120454191-B - Passive-based distributed cooperative control method for grid-formed inverter station

CN120454191BCN 120454191 BCN120454191 BCN 120454191BCN-120454191-B

Abstract

The invention discloses a passive-based distributed cooperative control method for a grid-formed inverter station, and belongs to the field of electrical engineering. The distributed cooperative control method designs the inner loop controller of the grid-structured inverter by using a port controlled Hamiltonian method, introduces a nonlinear observer to ensure the stability of a new energy station, determines ideal injection damping parameters of each grid-structured inverter in different power grid states by using a pole allocation method, and improves the dynamic performance of the grid-structured inverter station. The invention is simple to implement, solves the problem that the overall dynamic performance of the station is difficult to consider under the traditional passive control of the inverter in the multi-inverter scene in the grid-structured inverter station, and effectively improves the dynamic performance of the inverter station under the complex power grid change.

Inventors

LI MING
LIU ENJUN
MAO YONGTAO
WANG XING
ZHANG XING
GENG HUA
HE XIUQIANG
XIAO YANGJUN

Assignees

合肥工业大学

Dates

Publication Date: 20260512
Application Date: 20250427

Claims (6)

1. The distributed cooperative control method for the grid-formed inverter field station based on the passivity is characterized in that the grid-formed inverter field station refers to a power generation field station formed by n grid-formed inverters with the same structure, each grid-formed inverter comprises a direct-current side power supply, a three-phase inverter and an LC filter which are sequentially connected in series, the output ends of the n grid-formed inverters are connected in parallel and then connected to a three-phase power grid through a power grid inductor, and the distributed cooperative control method is characterized by comprising the following steps of: Step 1, establishing a mathematical model of a voltage current inner loop of a grid-built inverter, and marking the mathematical model as an inner loop mathematical model; step 2, according to the inner ring mathematical model in the step 1, a network-structured inverter inner ring port controlled Hamiltonian model is established and recorded as an inner ring Hamiltonian model, and an interconnection matrix is defined Damping matrix Hamiltonian , Is a state variable matrix; Step3, defining a nonlinear observer loop based on a port controlled Hamiltonian form, and recording the nonlinear observer loop as a nonlinear observer; Step 4, building an expected interconnection matrix And desired damping matrix The method comprises the following steps: ; Wherein, the In order to implant the interconnect matrix, In order to inject the damping matrix, And (3) with Is defined as: , Wherein the method comprises the steps of A damping is injected for the voltage loop, A damping is injected for the current loop, And (3) with As a function of the parameters to be determined, In order to filter the inductance value of the inductor, The capacitance value of the filter capacitor; Step 5, respectively defining state variable matrixes Matrix of desired state variables Closed loop Hamiltonian ; Step 6, building a desired closed loop Hamiltonian model according to the inner loop Hamiltonian model, a nonlinear observer and a closed loop Hamiltonian function, wherein the expression is as follows: ; Wherein, the Is the differentiation of the state variable matrix, Differentiation into a matrix of desired state variables; the voltage and current inner loop passive controller of the grid-structured inverter is designed according to the expected closed loop Hamiltonian model, so that the field station of the grid-structured inverter meets the passivity, and the stable operation of the field station of the grid-structured inverter is ensured; Step 7, designing voltage loop injection damping by using pole allocation method And current loop injection damping Is provided with a current loop injection damping And electric network inductance To a known amount, find the voltage loop injection damping Defining a first constraint relationship as Defining the second constraint relationship as According to And Obtaining different power grid inductances corresponding to each inverter in a network-structured inverter station The following satisfies the expected dynamic performance And Corresponding numerical values of the inverters, and realizing distributed cooperative control among the inverters.
2. The passive-based distributed cooperative control method of a grid-formed inverter station according to claim 1, wherein the expression of the inner loop mathematical model in step 1 is: ; Wherein, the In order to filter the inductance value of the inductor, For the capacitance value of the filter capacitor, For the d-axis component of the inverter output current, For the inverter to output the q-axis component of the current, For the derivative of the d-axis component of the inverter output current with respect to time, For the derivative of the inverter output current q-axis component with respect to time, For the d-axis component of the inverter output voltage, For the q-axis component of the inverter output voltage, For the derivative of the d-axis component of the inverter output voltage with respect to time, For the derivative of the inverter output voltage q-axis component with respect to time, In order to be of an angular frequency, As the d-axis component of the net side current, For the net side current q-axis component, For the parasitic resistance value of the filter inductance, The d-axis component of the voltage is modulated for the inverter, The q-axis component of the voltage is modulated for the inverter, For the voltage loop to perturb the d-axis component, For the voltage loop to perturb the q-axis component, For the current loop to perturb the d-axis component, The q-axis component is perturbed for the current loop.
3. The passive-based grid-formation inverter station distributed cooperative control method according to claim 2, wherein the expression of the inner ring hamilton model in step 2 is: ; Wherein, the In order to control the input matrix, In order to control the matrix of coefficients of the input matrix, For the external input matrix to be used, For the matrix of externally input matrix coefficients, For an unknown matrix of disturbances, For the matrix of unknown perturbation matrix coefficients, In the form of a hamiltonian, In the form of an interconnection matrix, Is a damping matrix; the interconnection matrix Damping matrix The expression of (2) is: ; ; Definition of Hamiltonian The method comprises the following steps: 。
4. the passive-based distributed cooperative control method of grid-connected inverter stations according to claim 3, wherein the expression of the nonlinear observer in step 3 is: ; Wherein, the Is an observed value of the state variable matrix, Is the derivative of the observed value of the state variable matrix, As an observation of an unknown disturbance matrix, Is the derivative of the observed value of the unknown disturbance matrix, For the first observer gain factor, For the second series of observer gains, In order to be able to achieve a desired interconnection matrix, Is a desired damping matrix.
5. The method of distributed cooperative control of grid-tied inverter stations based on passivity according to claim 4, wherein the state variable matrix of step 5 Matrix of desired state variables Closed loop Hamiltonian Is defined as: ; ; Wherein, the To expect the d-axis component of the inverter output current, To expect the inverter output current q-axis component, To expect the d-axis component of the inverter output voltage, To expect the q-axis component of the inverter output voltage, superscript Transpose of the representation matrix, Q is the filter parameter matrix, 。
6. The passive-based distributed cooperative control method of grid-tied inverter field station according to claim 5, wherein the specific steps of the step 7 are as follows: step 7.1, establishing a voltage loop open-loop continuous domain transfer function of the voltage current loop passive controller And current loop open loop continuous domain transfer function The expressions are respectively: ; Wherein the method comprises the steps of Is a Laplacian operator; According to And Multiplying to obtain the integral open loop continuous domain transfer function of the passive controller in the voltage and current loop The expression is: ; step 7.2, overall open loop continuous domain transfer function for a voltage current loop passive controller Discretizing by using a backward Euler method to obtain an integral open loop discrete domain transfer function of the voltage-current inner loop passive controller The expression is: ; Wherein, the For the sampling period, z is a discrete domain variable, , Is a Laplacian operator; Step 7.3, establishing a discrete domain transfer function of inverter side current to inverter output voltage The expression is: ; Wherein, the At the frequency of the resonance and, , As a first coefficient of simplification, B is a second reduction factor, , The inductance value is the inductance value of the power grid; step 7.4, the overall open loop discrete domain transfer function of the voltage-current inner loop passive controller according to step 7.2 And step 7.3 the inverter-side current-to-inverter output voltage discrete domain transfer function Calculating a closed loop discrete domain transfer function of a controller The expression is: ; step 7.5, according to the closed loop discrete domain transfer function of the controller Solving a characteristic equation of a closed loop discrete domain of the controller The method comprises the following steps: ; Step 7.6, selecting expected poles of the closed-loop discrete domain characteristic equation of the controller, and respectively defining dominant poles one Dominant pole two Non-dominant pole three Non-dominant pole four Five non-dominant poles Six non-dominant poles The expression is: ; Wherein, the In order to achieve a damping ratio, Is a natural frequency which is set to be a natural frequency, In units of imaginary numbers, Is a non-dominant pole coefficient; Step 7.7, according to the expected pole of the discrete domain characteristic equation of step 7.6, obtaining a controller expected closed loop discrete domain characteristic equation The expression is: ; Step 7.8, setting according to the closed-loop discrete domain characteristic equation of the controller in step 7.5 and the expected closed-loop discrete domain characteristic equation of the controller in step 7.7 Pole allocation is realized, and voltage loop injection damping is established And current loop injection damping Inductance with electric network Mathematical relationship between; with current loop injection damping And electric network inductance To a known amount, find the voltage loop injection damping Defining a first constraint relationship as The expression is: ; defining the second constraint relationship as The expression is: ; Step 7.9, two types of constraint relationships according to step 7.8 And Obtaining different power grid inductances corresponding to each inverter in a network-structured inverter station The following satisfies the expected dynamic performance And Corresponding numerical values of the inverters, and realizing distributed cooperative control among the inverters.

Description

Passive-based distributed cooperative control method for grid-formed inverter station Technical Field The invention belongs to the field of electrical engineering, and relates to a passive-based distributed cooperative control method for a grid-formed inverter station. Background As a key interface for grid-connected renewable energy power generation, the control performance of a grid-connected inverter is important for a multi-inverter power station. Currently, many researchers have proposed grid-built inverter control. These inverters are capable of supporting the grid frequency and voltage, making them a prominent area of current research, and a key trend in the development of large-scale renewable energy integration. Currently, these inverters generally employ linear controllers, such as proportional-integral control, which are designed based on linear theory. However, when non-linear changes occur in the power grid due to instability and volatility of the renewable energy source, such as plug and play of inverters in a multi-inverter power station, large fluctuations in the power grid impedance, and random changes in the operating point of the inverters, the structure and parameters of the power grid change randomly. In this case, a control scheme based on the linear theory may not ensure system stability. Previous studies have shown that problems such as wideband oscillations in the nonlinear frequency domain may occur, thereby presenting significant stability challenges. The article entitled "high-permeability New energy Power grid-connected converter and grid/grid-formation hybrid mode control overview" (Zhang Xing, war auspicious pair, wu Mengze, et cetera.) describes the features of grid-connected control and grid-formation control inverter control for high-permeability New energy Power grid-connected converter and grid/grid-formation hybrid mode control overview [ J ]. Electric Power System Automation, 2024,48 (21): 1-15 ]. Under the high-permeability new energy background, the new energy station is always in the weak power grid environment at the tail end, the inverter is poor in stability in the traditional grid-connected control with the grid, and the reverse grid-connected control is better in stability. However, when the grid structure and parameters vary randomly and widely, it still faces the challenge of maintaining stable operation, and resonance and instability problems of multiple inverter stations within the station remain. The problem of nonlinear oscillation easily occurs in a multi-inverter power station adopting conventional grid-connected control, and stability cannot be ensured under nonlinear disturbance. For high grid impedance and non-linear grid structure/parameter variation, existing studies propose passive control based on non-linear control theory, but it cannot be applied to distributed cooperative control of multiple inverters in a grid-built inverter station, for example: 1) The distributed coordination stable control of "Distributed Coordinated Control for Stabilization of Multi-Inverter Power Plant"(M.Li,H.Geng and X.Zhang,″Distributed Coordinated Control for Stabilization of Multi-Inverter Power Plant,″in IEEE Transactions on Industrial Electronics,vol.70,no.12,pp.12421-12430,Dec.2023)(" multi-inverter power station (M.Li, H.Geng and X.zhang), the distributed coordination stable control of multi-inverter power station [ J ], IEEE industry electronic journal, volume 70, 12 th period, page number: 12421-12430,2023 Defebruary.) designs a passive controller for the grid-following inverter, realizes the distributed coordination stable operation of the grid-following inverter station, can adapt to the change of nonlinear power grid structure/parameters, however, the design of the passive controller for the corresponding grid-following control of the inverter still has blank. 2) The invention discloses a grid-connected inverter grid-connected passive control parameter optimization method (publication No. CN 118264144A) based on data driving, which designs a passive controller of a grid-connected inverter and a method for optimizing injection damping parameters by using a particle swarm algorithm, but the design only relates to control parameters of a single inverter, and cannot be applied to grid-connected inverter stations formed by a plurality of grid-connected inverters, so that the synergistic effect among the grid-connected inverters cannot be ensured. 3) The invention relates to a control parameter optimization method and an optimization device (publication number CN 116404691A) of a network-structured new energy power generation system, which designs a passive controller of a network-structured inverter and designs parameters by using a D segmentation method, but the same design only relates to the design of control parameters of a single inverter and cannot be applied to a field station of the network-structured inverter. In summary, the prior art has the following