A passive-based distributed collaborative control method for grid-forming inverter station field

Abstract

The application discloses a kind of based on passive network type inverter station distributed collaborative control method, belong to electrical engineering field.The distributed collaborative control method is designed to the inner loop controller of network type inverter by using port controlled Hamilton method, and the stability of new energy station is guaranteed by introducing nonlinear observer, in addition, the ideal injection damping parameters of each network type inverter under different power grid states are determined by using pole placement method, and the dynamic performance of network type inverter station is improved.The application is not only simple to implement, but also solves the problem that the overall dynamic performance of the station is difficult to be considered under the traditional passive control of the inverters in the network type inverter station scene with multiple inverters, effectively improving the dynamic performance of the inverter station under complex power grid changes.

Description

Technical Field

[0001] This invention belongs to the field of electrical engineering and relates to a distributed collaborative control method for grid-connected inverters in power plants based on passive operation. Background Technology

[0002] As a crucial interface for grid-connected renewable energy generation, the control performance of grid-connected inverters is vital for multi-inverter power plants. Currently, many researchers have proposed grid-connected inverter control. These inverters can support grid frequency and voltage, making them a prominent research area and a key trend in the large-scale integrated development of renewable energy. Currently, these inverters typically employ linear controllers, such as proportional-integral (PI) control, which is designed based on linear theory. However, when nonlinear changes occur in the grid due to the instability and volatility of renewable energy, such as the plug-and-play nature of inverters in multi-inverter power plants, large fluctuations in grid impedance, and random changes in the inverter's operating point, the grid structure and parameters change randomly. In such cases, linear theory-based control schemes may not be able to ensure system stability. Previous studies have shown that problems such as broadband oscillations in the nonlinear frequency domain may arise, posing significant stability challenges.

[0003] An article titled "A Review of Hybrid Control Modes for Grid-Connected / Grid-Building Converters in High-Penetration New Energy Power Generation" (Zhang Xing, Zhan Xiangdui, Wu Mengze, et al. A Review of Hybrid Control Modes for Grid-Connected / Grid-Building Converters in High-Penetration New Energy Power Generation [J]. Automation of Electric Power Systems, 2024, 48(21): 1-15.) introduces the characteristics of grid-connected and grid-building control inverters. In the context of high-penetration new energy, new energy power plants are often located in weak grid environments at the end of the grid. Traditional grid-connected control of inverters exhibits poor stability, while grid-building control offers better stability. However, when the grid structure and parameters change randomly and over a wide range, it still faces the challenge of maintaining stable operation. Resonance and instability problems in multi-inverter power plants within the plant still exist. Multi-inverter power plants using conventional grid-building control are prone to nonlinear oscillations and cannot guarantee stability under nonlinear disturbances.

[0004] To address the challenges of high grid impedance and variations in nonlinear grid structure / parameters, existing research proposes passive control based on nonlinear control theory. However, this approach is not applicable to the distributed collaborative control of multiple inverters within grid-connected inverter sites, for example:

[0005] 1) The title is "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). A passive controller was designed for grid-connected inverters, realizing the distributed coordinated and stable operation of grid-connected inverter power plants. It can adapt to changes in nonlinear grid structure / parameters. However, the design of a passive controller for grid-connected inverter control still has a gap.

[0006] 2) Invention Patent: Data-driven method for optimizing passive control parameters of grid-connected inverters (Publication No. CN118264144A) designed a passive controller for grid-connected inverters and a method for optimizing injected damping parameters using particle swarm optimization. However, its design only involves the control parameters of a single inverter and cannot be applied to grid-connected inverter plants composed of multiple grid-connected inverters, thus failing to guarantee the synergistic effect between multiple grid-connected inverters.

[0007] 3) Invention Patent: A method and device for optimizing control parameters of a grid-type new energy power generation system (Publication No. CN116404691A) designed a passive controller for a grid-type inverter and used the D-segmentation method to design parameters. However, it only involves the design of control parameters for a single inverter and cannot be applied to grid-type inverter power plants.

[0008] In summary, the existing technology has the following problems:

[0009] (1) Existing grid-type inverter control technology lacks the ability to cope with changes in nonlinear grid conditions and parameters, especially in multi-inverter sites, where it is difficult to take into account the control performance of each inverter.

[0010] (2) The nonlinear distributed passive control strategy for multi-inverter stations proposed in the existing technology only involves grid-connected inverters, while the passive control design corresponding to grid-connected inverters is still lacking. Summary of the Invention

[0011] The technical problem to be solved by this invention is that traditional grid-based control is difficult to cope with nonlinear changes in grid state and parameters, and the dynamic performance of multiple inverters within the power station is difficult to coordinate. Therefore, it is necessary to propose a nonlinear grid-based distributed cooperative control.

[0012] The objective of this invention is achieved as follows: This invention provides a distributed collaborative control method for a passive grid-connected inverter power station. The grid-connected inverter power station refers to a power generation station composed of n identical grid-connected inverters. Each grid-connected inverter includes a DC-side power supply, a three-phase inverter, and an LC filter connected in series. The outputs of the n grid-connected inverters are connected in parallel and then connected to the three-phase power grid through a grid inductor. The steps of the collaborative control method are as follows:

[0013] Step 1: Establish a mathematical model of the voltage and current inner loop of the grid-connected inverter, and denote it as the inner loop mathematical model;

[0014] Step 2: Based on the inner-loop mathematical model described in Step 1, establish the controlled Hamiltonian model of the inner-loop port of the grid-type inverter, and denote it as the inner-loop Hamiltonian model; define the interconnection matrix J(x), the damping matrix R(x), and the Hamiltonian function H(x), where x is the state variable matrix;

[0015] Step 3: Define a nonlinear observer loop based on the port-controlled Hamiltonian form, denoted as the nonlinear observer;

[0016] Step 4, establish the desired interconnection matrix J d (x) and the desired damping matrix R d (x) is:

[0017]

[0018] Among them, J a (x) is the injection interconnection matrix, R a (x) is the injection damping matrix, the injection damping matrix R a (x) is related to voltage loop injection damping r1 and current loop injection damping r2, which are undetermined parameters;

[0019] Step 5: Define the state variable matrix x and the desired state variable matrix x', respectively. d and the closed-loop Hamiltonian function H d (xx d );

[0020] Step 6: Based on the inner-loop Hamiltonian model, the nonlinear observer, and the closed-loop Hamiltonian function, establish the desired closed-loop Hamiltonian model, whose expression is:

[0021]

[0022] in, The differential of the state variable matrix, The derivative of the desired state variable matrix;

[0023] Based on the desired closed-loop Hamiltonian model, a passive voltage and current inner loop controller for the grid-type inverter is designed, which enables the grid-type inverter site to meet the passivity requirement and ensures the stable operation of the grid-type inverter site.

[0024] Step 7: Using the pole placement method, design the parameter adaptive law for voltage loop injection damper r1 and current loop injection damper r2 to realize distributed collaborative control among multiple grid-type inverters in the grid-type inverter field and optimize the dynamic performance of the grid-type inverter field.

[0025] Preferably, the expression for the inner loop mathematical model in step 1 is:

[0026]

[0027] Where L is the inductance of the filter inductor, C is the capacitance of the filter capacitor, and i d i represents the d-axis component of the inverter output current. q This represents the q-axis component of the inverter output current. Let be the time derivative of the d-axis component of the inverter output current. Let v be the time derivative of the q-axis component of the inverter output current. Cd v is the d-axis component of the inverter output voltage. Cq This represents the q-axis component of the inverter output voltage. Let be the derivative of the d-axis component of the inverter output voltage with respect to time. Let ω be the derivative of the q-axis component of the inverter output voltage with respect to time, and i be the angular frequency. gd i represents the d-axis component of the grid-side current. gq For the q-axis component of the grid-side current, r f V is the parasitic resistance value of the filter inductor. d For the d-axis component of the inverter modulation voltage, v q γ is the q-axis component of the inverter modulation voltage. vd For the d-axis component of the voltage loop disturbance, γ vq For the q-axis component of the voltage loop disturbance, γ id For the d-axis component of the current loop disturbance, γ iq This represents the q-axis component of the current loop disturbance.

[0028] Preferably, the expression for the inner-loop Hamiltonian model in step 2 is:

[0029]

[0030] Among them, u c To control the input matrix, g c To control the input matrix coefficient matrix, u e For the external input matrix, g e Let p be the external input matrix and g be the coefficient matrix, where p is the unknown perturbation matrix. p Let H(x) be the coefficient matrix of the unknown perturbation matrix, H(x) be the Hamiltonian function, J(x) be the interconnection matrix, and R(x) be the damping matrix.

[0031] The expressions for the interconnection matrix J(x) and the damping matrix R(x) are as follows:

[0032]

[0033] Define the Hamiltonian function H(x) as:

[0034]

[0035] Preferably, the expression for the nonlinear observer in step 3 is:

[0036]

[0037] in, The observed values ​​are the state variable matrix. The derivative of the observed values ​​of the state variable matrix. For the observed values ​​of the unknown perturbation matrix, J is the differential of the observed values ​​of the unknown perturbation matrix, k1 is the gain coefficient of the first observer, k2 is the gain coefficient of the second observer, and J is the differential of the observed values ​​of the unknown perturbation matrix. d (x) is the desired interconnection matrix, R d (x) is the desired damping matrix.

[0038] Preferably, the injected interconnect matrix J in step 4 a (x) and the injection damping matrix R a (x) is defined as:

[0039]

[0040] Preferably, the state variable matrix x and the desired state variable matrix x in step 5 are... d and the closed-loop Hamiltonian function H d (xx d The definitions of ) are as follows:

[0041]

[0042] in, For the desired d-axis component of the inverter output current, For the desired q-axis component of the inverter output current, For the desired d-axis component of the inverter output voltage, Let T be the q-axis component of the desired inverter output voltage, with the superscript T indicating matrix transpose; Q is the filter parameter matrix, Q = diag(L, L, C, C).

[0043] Preferably, the specific steps of step 7 are as follows:

[0044] Step 7.1: Establish the open-loop continuous domain transfer function G of the voltage loop for the passive voltage and current inner-loop controller. v (s) and the open-loop continuous-domain transfer function G of the current loop c (s), the expressions are as follows:

[0045]

[0046] Where s is the Laplace operator;

[0047] According to G v (s) and G c (s), multiplied together, yields the overall open-loop continuous domain transfer function G of the voltage and current inner-loop passive controller. i (s), whose expression is:

[0048] G i (s)=G v (s)·G c (s)=r1r2+(r1L+r2C)s+LCs 2 ;

[0049] Step 7.2, the overall open-loop continuous domain transfer function G of the voltage and current inner loop passive controller is... i (s) Discretize using the backward Euler method to obtain the global open-loop discrete domain transfer function G of the voltage and current inner loop passive controller. i (z), its expression is:

[0050]

[0051] Among them, T s Let z be the sampling period, and z be a discrete-domain variable. s is the Laplace operator;

[0052] Step 7.3: Establish the discrete-domain transfer function G of inverter-side current on inverter output voltage. LCL (z), its expression is:

[0053]

[0054] Where, ω r The resonant frequency, 'a' is the first simplification coefficient. b is the second simplification coefficient. L g This is the inductance value of the power grid inductor;

[0055] Step 7.4, based on the overall open-loop discrete domain transfer function G of the voltage and current inner-loop passive controller described in step 7.2. i (z) and the discrete-domain transfer function GL of the inverter-side current to the inverter output voltage described in step 7.3. CL (z), calculate the discrete domain transfer function G(z) of the controller closed loop, its expression is:

[0056] G(z)=z -1 G i (z)G LCL (z) / [1+z -1 G i (z)G LCL (z)];

[0057] Step 7.5: Based on the controller's closed-loop discrete-domain transfer function G(z), obtain the controller's closed-loop discrete-domain characteristic equation A. c (z -1 )for:

[0058]

[0059] Step 7.6: Select the desired poles of the characteristic equation of the closed-loop discrete domain of the controller, and define the dominant pole 1 z1, dominant pole 2 z2, non-dominant pole 3 z3, non-dominant pole 4 z4, non-dominant pole 5 z5, and non-dominant pole 6 z6 respectively. The expression is as follows:

[0060]

[0061] Where ξ is the damping ratio, ω n is the natural frequency, j is the imaginary unit, and m is the non-dominant pole coefficient;

[0062] Step 7.7: Based on the desired poles of the discrete-domain characteristic equation obtained in Step 7.6, obtain the desired closed-loop discrete-domain characteristic equation A of the controller. m (z -1 The expression is:

[0063]

[0064] Step 7.8: Based on the controller closed-loop discrete domain characteristic equation described in step 7.5 and the controller desired closed-loop discrete domain characteristic equation described in step 7.7, set A... m (z -1 ) = A c (z -1 To achieve pole placement, establish voltage loop injection damping r1 and current loop injection damping r2 relative to the grid inductance L. g The mathematical relationship between them;

[0065] Assume the current loop injection damping r2 and the grid inductance L g Given the quantities, determine the two types of constraint relationships of the voltage loop injection damping with respect to r1. Define the first constraint relationship as r1 = f(r2, L). g Its expression is:

[0066]

[0067] Define the second constraint relationship as r1 = g(r2, L) g Its expression is:

[0068]

[0069] Step 7.9, based on the two types of constraint relationships r1=f(r2, L) in step 7.8 g ) and r1=g(r2,L g ), to obtain the grid inductance L of each inverter in the grid-connected inverter field for different grid inductances. g The corresponding values ​​of r1 and r2 are set to satisfy the desired dynamic performance, thereby realizing distributed collaborative control among the inverters.

[0070] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0071] 1. The grid-type inverter control method provided by the present invention is simple to implement. It only requires adaptive adjustment of the injection damping according to the grid impedance after the controller is designed, which can improve the dynamic performance of the grid-type inverter.

[0072] 2. The passive controller designed based on nonlinear theory in this invention enables the inverter to remain stable under complex nonlinear changes in grid conditions and parameters. Its stability in high-penetration new energy grids is superior to that of controllers designed under traditional linear frameworks.

[0073] 3. This invention introduces a nonlinear state observer into the voltage and current inner loop controller of the grid-type inverter, which can effectively cope with unknown external disturbances to the inverter, enabling the inverter output to achieve error-free tracking. At the same time, the nonlinear state observer is based on a passive design and remains stable.

[0074] 4. The passive controller and injection damping adaptive adjustment method designed in this invention are designed from the perspective of multiple machines. In inverter stations with a large number of grid-type inverters, distributed collaborative control of each inverter can be achieved, thereby reducing mutual interference between inverters and ensuring that the station as a whole has good dynamic performance. Attached Figure Description

[0075] Figure 1 This is a structural diagram of the grid-type inverter field station described in this invention.

[0076] Figure 2 This is a control block diagram of the distributed collaborative control method described in this invention.

[0077] Figure 3 This is a graph showing the relationship between the injected damping value and the grid inductance described in this invention.

[0078] Figure 4 The simulation waveforms are shown for the fixed injection damping control method.

[0079] Figure 5 The simulation waveform diagram shows the distributed cooperative control method of this invention. Detailed Implementation

[0080] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0081] Figure 1 This is a structural diagram of the grid-type inverter field station described in this invention. Figure 1 As can be seen, the grid-type inverter power station refers to a power generation station composed of n grid-type inverters with the same structure. Each grid-type inverter includes a DC-side power supply, a three-phase inverter and an LC filter connected in series in sequence. The output terminals of the n grid-type inverters are connected in parallel and then connected to the three-phase power grid through the grid inductor.

[0082] exist Figure 1 In the middle, V DC The voltage is the DC side voltage. 1# is the number of the first inverter, 2# is the number of the second inverter, and n# is the number of the nth inverter.

[0083] Figure 2 This is a control block diagram of the distributed cooperative control method described in this invention. Figure 2 As can be seen, this invention provides a distributed cooperative control method for grid-connected inverter power plants based on passive operation, comprising the following steps. Steps 1, 2, and 6 establish the passive voltage-current inner-loop controller; steps 3 to 5 establish the nonlinear observer; and step 7 establishes the adaptive damping cooperative element. e As a control signal input Figure 1In the corresponding three-phase inverter, the control of the three-phase inverter is realized.

[0084] Step 1: Establish a mathematical model of the voltage and current inner loop of the grid-connected inverter, and denote it as the inner loop mathematical model.

[0085] In this embodiment, the expression for the inner loop mathematical model is:

[0086]

[0087] Where L is the inductance of the filter inductor, C is the capacitance of the filter capacitor, and i d i represents the d-axis component of the inverter output current. q This represents the q-axis component of the inverter output current. Let be the time derivative of the d-axis component of the inverter output current. Let v be the time derivative of the q-axis component of the inverter output current. Cd v is the d-axis component of the inverter output voltage. Cq This represents the q-axis component of the inverter output voltage. Let be the derivative of the d-axis component of the inverter output voltage with respect to time. Let ω be the derivative of the q-axis component of the inverter output voltage with respect to time, and i be the angular frequency. gd i represents the d-axis component of the grid-side current. gq For the q-axis component of the grid-side current, r f V is the parasitic resistance value of the filter inductor. d For the d-axis component of the inverter modulation voltage, v q γ is the q-axis component of the inverter modulation voltage. vd For the d-axis component of the voltage loop disturbance, γ vq For the q-axis component of the voltage loop disturbance, γ id For the d-axis component of the current loop disturbance, γ iq This represents the q-axis component of the current loop disturbance.

[0088] Step 2: Based on the inner-loop mathematical model described in Step 1, establish the controlled Hamiltonian model of the inner-loop port of the grid-type inverter, and denot it as the inner-loop Hamiltonian model; define the interconnection matrix J(x), the damping matrix R(x), and the Hamiltonian function H(x), where x is the state variable matrix.

[0089] In this embodiment, the expression for the inner-loop Hamiltonian model is:

[0090]

[0091] Where x represents the state variable matrix, u c To control the input matrix, g c To control the input matrix coefficient matrix, u e For the external input matrix, ge Let p be the external input matrix and g be the coefficient matrix, where p is the unknown perturbation matrix. p Let H(x) be the coefficient matrix of the unknown perturbation matrix, H(x) be the Hamiltonian function, J(x) be the interconnection matrix, and R(x) be the damping matrix.

[0092] The expressions for the interconnection matrix J(x) and the damping matrix R(x) are as follows:

[0093]

[0094] Define the Hamiltonian function H(x) as:

[0095]

[0096] Step 3: Define a nonlinear observer loop based on the port-controlled Hamiltonian form, denoted as the nonlinear observer.

[0097] In this embodiment, the expression for the nonlinear observer is:

[0098]

[0099] in, The observed values ​​are the state variable matrix. The derivative of the observed values ​​of the state variable matrix. For the observed values ​​of the unknown perturbation matrix, The derivative of the observed values ​​of the unknown perturbation matrix is ​​given by x, where k1 is the gain coefficient of the first observer, k2 is the gain coefficient of the second observer, and x is the derivative of the observed values ​​of the unknown perturbation matrix. d Let H be the desired state variable matrix. d (xx d J is the closed-loop Hamiltonian function. d (x) is the desired interconnection matrix, R d (x) is the desired damping matrix.

[0100] Step 4, establish the desired interconnection matrix J d (x) and the desired damping matrix R d (x) is:

[0101]

[0102] Among them, J a (x) is the injection interconnection matrix, R a (x) is the injection damping matrix, the injection damping matrix R a (x) The voltage loop injection damping r1 and the current loop injection damping r2 are related, and the voltage loop injection damping r1 and the current loop injection damping r2 are undetermined parameters;

[0103] In this embodiment, the injected interconnect matrix Ja (x) and the injection damping matrix R a (x) is defined as:

[0104]

[0105] Step 5: Define the state variable matrix x and the desired state variable matrix x', respectively. d and the closed-loop Hamiltonian function H d (xx d ).

[0106] In this embodiment, the state variable matrix x and the desired state variable matrix x d and the closed-loop Hamiltonian function H d (xx d The definitions of ) are as follows:

[0107]

[0108]

[0109] in, For the desired d-axis component of the inverter output current, For the desired q-axis component of the inverter output current, For the desired d-axis component of the inverter output voltage, Let T be the q-axis component of the desired inverter output voltage, with the superscript T indicating matrix transpose; Q is the filter parameter matrix, Q = diag(L, L, C, C).

[0110] Step 6: Based on the inner-loop Hamiltonian model, the nonlinear observer, and the closed-loop Hamiltonian function, establish the desired closed-loop Hamiltonian model, whose expression is:

[0111]

[0112] in, The differential of the state variable matrix, The derivative of the desired state variable matrix;

[0113] Based on the desired closed-loop Hamiltonian model, a passive voltage and current inner loop controller for the grid-type inverter is designed, which enables the grid-type inverter site to meet the passivity requirement and ensures the stable operation of the grid-type inverter site.

[0114] Step 7: Using the pole placement method, design the parameter adaptive law for voltage loop injection damper r1 and current loop injection damper r2 to realize distributed collaborative control among multiple grid-type inverters in the grid-type inverter field and optimize the dynamic performance of the grid-type inverter field.

[0115] In this embodiment, step 7 is performed as follows:

[0116] Step 7.1: Establish the open-loop continuous domain transfer function G of the voltage loop for the passive voltage and current inner-loop controller. v (s) and the open-loop continuous-domain transfer function G of the current loop c (s), the expressions are as follows:

[0117]

[0118] Where s is the Laplace operator;

[0119] According to G v (s) and G c (s), multiplied together, yields the overall open-loop continuous domain transfer function G of the voltage and current inner-loop passive controller. i (s), whose expression is:

[0120] G i (s)=G v (s)·G c (s)=r1r2+(r1L+r2C)s+LCs 2 ;

[0121] Step 7.2, the overall open-loop continuous domain transfer function G of the voltage and current inner loop passive controller is... i (s) Discretize using the backward Euler method to obtain the global open-loop discrete domain transfer function G of the voltage and current inner loop passive controller. i (z), its expression is:

[0122]

[0123] Among them, T s Let z be the sampling period, and z be a discrete-domain variable. s is the Laplace operator;

[0124] Step 7.3: Establish the discrete-domain transfer function G of inverter-side current on inverter output voltage. LCL (z), its expression is:

[0125]

[0126] Where, ω r The resonant frequency, 'a' is the first simplification coefficient. b is the second simplification coefficient. L g This is the inductance value of the power grid inductor;

[0127] Step 7.4, based on the overall open-loop discrete domain transfer function G of the voltage and current inner-loop passive controller described in step 7.2. i(z) and the discrete-domain transfer function G of the inverter-side current to the inverter output voltage described in step 7.3. LCL (z), calculate the discrete domain transfer function G(z) of the controller closed loop, its expression is:

[0128] G(z)=z -1 G i (z)G LCL (z) / [1+z -1 G i (z)G LCL (z)];

[0129] Step 7.5: Based on the controller's closed-loop discrete-domain transfer function G(z), obtain the controller's closed-loop discrete-domain characteristic equation A. c (z -1 )for:

[0130]

[0131] Step 7.6: Select the desired poles of the characteristic equation of the closed-loop discrete domain of the controller, and define the dominant pole 1 z1, dominant pole 2 z2, non-dominant pole 3 z3, non-dominant pole 4 z4, non-dominant pole 5 z5, and non-dominant pole 6 z6 respectively. The expression is as follows:

[0132]

[0133] Where ξ is the damping ratio, ω n is the natural frequency, j is the imaginary unit, and m is the non-dominant pole coefficient;

[0134] Step 7.7: Based on the desired poles of the discrete-domain characteristic equation obtained in Step 7.6, obtain the desired closed-loop discrete-domain characteristic equation A of the controller. m (z -1 The expression is:

[0135]

[0136] Step 7.8: Based on the controller closed-loop discrete domain characteristic equation described in step 7.5 and the controller desired closed-loop discrete domain characteristic equation described in step 7.7, set A... m (z -1 ) = A c (z -1 To achieve pole placement, establish voltage loop injection damping r1 and current loop injection damping r2 relative to the grid inductance L. g The mathematical relationship between them;

[0137] Assume the current loop injection damping r2 and the grid inductance L gGiven the quantities, determine the two types of constraint relationships of the voltage loop injection damping with respect to r1. Define the first constraint relationship as r1 = f(r2, L). g Its expression is:

[0138]

[0139] Define the second constraint relationship as r1 = g(r2, L) g Its expression is:

[0140]

[0141] Step 7.9, based on the two types of constraint relationships r1=f(r2, L) in step 7.8 g ) and r1=g(r2,L g ), to obtain the grid inductance L of each inverter in the grid-connected inverter field for different grid inductances. g The corresponding values ​​of r1 and r2 are set to satisfy the desired dynamic performance, thereby realizing distributed collaborative control among the inverters.

[0142] To demonstrate the distributed collaborative control method for grid-connected inverters based on passive architecture provided in this invention, simulations were performed.

[0143] This simulation uses n=2, that is, two three-phase inverters are used for verification, which are denoted as inverter 1 and inverter 2 respectively.

[0144] The relevant electrical parameters for this simulation are set as follows: Active power reference value P1 of inverter 1. * =20kW, active power reference value of inverter 2 Damping ratio ξ = 0.707, natural frequency ω n =314 rad / s, non-dominant pole coefficient m=10.

[0145] Figure 3 The graph shows the relationship between the injection damping values ​​of inverter 1 and inverter 2 and the grid inductance under corresponding parameters. Different grid inductances correspond to different values ​​of voltage loop injection damping r1 and current loop injection damping r2.

[0146] Figure 4 Power waveform diagram when the same fixed injection damping parameters are used for inverter 1 and inverter 2. Figure 4 As can be seen, at time 1 second, the active power reference values ​​of inverter 1 and inverter 2 increase due to simulated disturbance, and the active power waveform shows obvious oscillation.

[0147] Figure 5 The power waveform diagram of the adaptive given condition when damping is injected into inverter 1 and inverter 2 using the distributed cooperative control method of this invention is shown. Figure 5As can be seen, at time 1 second, the active power reference values ​​of inverter 1 and inverter 2 increase with simulated disturbance, and the active power waveform oscillation is effectively suppressed.

[0148] In summary, Figure 4 , Figure 5 The simulated waveform shown conforms to the results of this invention, effectively suppressing active power oscillations under system disturbances and improving the dynamic performance of the system.

Claims

1. A distributed collaborative control method for a passive grid-type inverter power station, wherein the grid-type inverter power station refers to a power generation station composed of n identical grid-type inverters, wherein each grid-type inverter includes a DC-side power supply, a three-phase inverter, and an LC filter connected in series in sequence, and the output terminals of the n grid-type inverters are connected in parallel and then connected to the three-phase power grid through a grid inductor; characterized in that, The steps of the collaborative control method are as follows: Step 1: Establish a mathematical model of the voltage and current inner loop of the grid-connected inverter, and denote it as the inner loop mathematical model; Step 2: Based on the inner-loop mathematical model described in Step 1, establish a controlled Hamiltonian model for the inner-loop ports of the grid-connected inverter, denoted as the inner-loop Hamiltonian model; define the interconnection matrix. Damping matrix and Hamiltonian function , The state variable matrix; Step 3: Define a nonlinear observer loop based on the port-controlled Hamiltonian form, denoted as the nonlinear observer; Step 4, establish the desired interconnection matrix With the expected damping matrix for: ； in, To inject the interconnect matrix, To inject the damping matrix, and Defined as: ， in Inject damping into the voltage loop. Inject damping into the current loop. and These are parameters to be determined. This is the inductance value of the filter inductor. This is the capacitance value of the filter capacitor; Step 5, define the state variable matrices respectively. Expected state variable matrix and closed-loop Hamiltonian function ; Step 6: Based on the inner-loop Hamiltonian model, the nonlinear observer, and the closed-loop Hamiltonian function, establish the desired closed-loop Hamiltonian model, whose expression is: ； in, The differential of the state variable matrix, The derivative of the desired state variable matrix; Based on the desired closed-loop Hamiltonian model, a passive voltage and current inner loop controller for the grid-type inverter is designed, which enables the grid-type inverter site to meet the passivity requirement and ensures the stable operation of the grid-type inverter site. Step 7: Using the pole placement method, design the voltage loop injection damping. and current loop injection damping The parameter adaptive law, assuming current loop injection damping. and grid inductance Given the quantities, calculate the voltage loop injection damping with respect to... There are two types of constraint relationships. The first constraint relationship is defined as... Define the second constraint relationship as ,according to and To obtain the inductance of each inverter in a grid-connected inverter field at different grid inductances. The following satisfies the desired dynamic performance and The corresponding values ​​enable distributed collaborative control among the inverters.

2. The distributed collaborative control method for a passive grid-type inverter station according to claim 1, characterized in that, The expression for the inner loop mathematical model described in step 1 is: ； in, This is the inductance value of the filter inductor. This is the capacitance value of the filter capacitor. This represents the d-axis component of the inverter output current. This represents the q-axis component of the inverter output current. Let be the time derivative of the d-axis component of the inverter output current. This is the time derivative of the q-axis component of the inverter output current. The d-axis component of the inverter output voltage. This represents the q-axis component of the inverter output voltage. Let be the derivative of the d-axis component of the inverter output voltage with respect to time. This is the time derivative of the q-axis component of the inverter output voltage. Angular frequency, The d-axis component of the grid-side current. This represents the q-axis component of the grid-side current. This is the parasitic resistance value of the filter inductor. The d-axis component of the inverter modulation voltage. The q-axis component of the inverter modulation voltage. The voltage loop perturbation is represented by the d-axis component. This represents the q-axis component of the voltage loop disturbance. The d-axis component represents the current loop disturbance. This represents the q-axis component of the current loop disturbance.

3. The distributed collaborative control method for a passive grid-type inverter station according to claim 2, characterized in that, The expression for the inner-loop Hamiltonian model described in step 2 is: ； in, To control the input matrix, To control the input matrix coefficient matrix, For the external input matrix, The external input matrix is ​​the coefficient matrix. The disturbance matrix is ​​unknown. The coefficient matrix is ​​an unknown perturbation matrix. For Hamiltonian functions, For interconnection matrix, Here is the damping matrix; The interconnection matrix and damping matrix The expression is: ； ； Define Hamiltonian function for: 。 4. The distributed collaborative control method for a passive grid-type inverter power station according to claim 3, characterized in that, The expression for the nonlinear observer described in step 3 is: ； in, The observed values ​​are the state variable matrix. The derivative of the observed values ​​of the state variable matrix. For the observed values ​​of the unknown perturbation matrix, The derivative of the observed values ​​of the unknown perturbation matrix. The gain coefficient of the first observer. For the second observer gain system, For the desired interconnect matrix, Let be the desired damping matrix.

5. The distributed collaborative control method for a passive grid-type inverter power station according to claim 4, characterized in that, The state variable matrix described in step 5 Expected state variable matrix and closed-loop Hamiltonian function The definitions are as follows: ； ； in, For the desired d-axis component of the inverter output current, For the desired q-axis component of the inverter output current, For the desired d-axis component of the inverter output voltage, The superscript represents the q-axis component of the desired inverter output voltage. This represents the matrix transpose; Q is the filter parameter matrix. .

6. The distributed collaborative control method for a passive grid-type inverter station according to claim 5, characterized in that, The specific steps of step 7 are as follows: Step 7.1: Establish the open-loop continuous domain transfer function of the voltage loop for the passive voltage and current inner-loop controller. and the open-loop continuous domain transfer function of the current loop The expressions are as follows: ； in For the Laplace operator; according to and Multiplying these values ​​yields the overall open-loop continuous domain transfer function of the voltage and current inner-loop passive controller. Its expression is: ； Step 7.2, the overall open-loop continuous domain transfer function of the voltage and current inner loop passive controller. Discretization using the Euler method yields the overall open-loop discrete-domain transfer function of the voltage and current inner-loop passive controller. Its expression is: ； in, Let z be the sampling period, and z be a discrete-domain variable. , For the Laplace operator; Step 7.3: Establish the discrete-domain transfer function of inverter-side current on inverter output voltage. Its expression is: ； in, The resonant frequency, , The first simplification coefficient, , b The second simplification coefficient, , This is the inductance value of the power grid inductor; Step 7.4, based on the overall open-loop discrete domain transfer function of the voltage and current inner-loop passive controller described in step 7.

2. And the discrete-domain transfer function of inverter-side current to inverter output voltage described in step 7.3 Calculate the discrete domain transfer function of the controller closed loop. Its expression is: ； Step 7.5, based on the controller closed-loop discrete domain transfer function The characteristic equation of the controller closed-loop discrete domain is obtained. for: ； Step 7.6: Select the desired poles of the characteristic equation of the closed-loop discrete domain of the controller, and define the dominant poles respectively. Dominant pole two Non-dominant pole three Non-dominant pole four Non-dominant pole five Non-dominant pole six The expression is: ； in, For the damping ratio, For natural frequency, The imaginary unit, These are non-dominant pole coefficients; Step 7.7: Based on the desired poles of the discrete-domain characteristic equation obtained in Step 7.6, derive the desired closed-loop discrete-domain characteristic equation of the controller. The expression is: ； Step 7.8: Based on the controller closed-loop discrete domain characteristic equation described in Step 7.5 and the controller desired closed-loop discrete domain characteristic equation described in Step 7.7, set... To achieve pole placement and establish voltage loop injection damping and current loop injection damping With grid inductance The mathematical relationship between them; Assume current loop injection damping and grid inductance Given the quantities, calculate the voltage loop injection damping with respect to... There are two types of constraint relationships. The first constraint relationship is defined as... Its expression is: ； Define the second constraint relationship as follows Its expression is: ； Step 7.9, based on the two types of constraint relationships in step 7.8 and To obtain the inductance of each inverter in a grid-connected inverter field at different grid inductances. The following satisfies the desired dynamic performance and The corresponding values ​​enable distributed collaborative control among the inverters.

Images