Photovoltaic system grid-connected oscillation control method and device through synchronous machine and storage medium

Abstract

In order to solve the problem of subsynchronous oscillation caused by weak damping of a photovoltaic grid-connected converter, the invention provides a grid-connected oscillation control method and device for a photovoltaic system through a synchronous machine and a storage medium. The invention relates to a photovoltaic grid-connected oscillation control technology. A synchronous motor excitation system is configured for a synchronous motor in the synchronous machine, and a synchronous generator excitation system is configured for a synchronous generator in the synchronous machine; performing interference modeling on a circuit of a photovoltaic system connected with a grid through a synchronous machine to obtain an interference model; solving eigenvalues and eigenvectors of a system matrix A of the interference model, obtaining oscillation modes based on the eigenvectors, obtaining damping ratios based on the eigenvectors, optimizing deviation of excitation voltages of the synchronous motor and the synchronous generator by taking minimization of differences between the damping ratios of the oscillation modes and a reference damping ratio as a target, and providing damping for various oscillation modes. Oscillation of each oscillation mode during grid connection is effectively suppressed.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic grid-connected oscillation control, and in particular to a photovoltaic system grid-connected oscillation control method, device and storage medium via a synchronous machine. Background Art

[0002] In the structure where the photovoltaic module is connected to the grid through a synchronous machine, after the synchronous machine is connected in series to the filter inductor circuit connected to the photovoltaic inverter, the synchronous machine includes a synchronous motor M and a synchronous generator G. The synchronous motor M is connected to the synchronous generator G through a mechanical shaft. The photovoltaic module outputs direct current to the inverter. The inverter converts the electrical quantity collected by the control system and outputs three-phase alternating current to drive the synchronous motor M to rotate, and drives the synchronous generator G to rotate. The energy change form of the synchronous machine during operation is converted from electrical energy to mechanical energy and then to electrical energy. After the photovoltaic system adopts the synchronous machine grid-connected mode, the power supply transitions from the oscillation form dominated by the photovoltaic system power electronic devices to the oscillation form dominated by the synchronous machine. The damping characteristics of the synchronous machine grid-connected system affect the oscillation. Summary of the invention

[0003] In order to solve the above technical problems or at least partially solve the above technical problems, the present invention provides a method, device and storage medium for controlling oscillation of a photovoltaic system connected to the grid via a synchronous machine.

[0004] In a first aspect, the present invention provides a method for controlling oscillation of a photovoltaic system connected to the grid via a synchronous machine, comprising: A synchronous motor excitation system is configured for the synchronous motor in the synchronous machine, and a synchronous generator excitation system is configured for the synchronous generator in the synchronous machine; The interference model of the photovoltaic system connected to the grid through the synchronous machine is obtained by interference modeling as follows: , , , Among them, ∆x is the state variable of the disturbance model, ∆u is the input variable of the disturbance model, A is the disturbance model system matrix, B is the input matrix, is the deviation of the DC side capacitor voltage, and are the deviations of the d-axis and q-axis components of the inverter output voltage, , , is the controller internal state variable, is the power angle deviation of the synchronous machine, is the synchronous machine rotor angular velocity deviation, and are the excitation flux deviations of synchronous motor and synchronous generator respectively, is the external light intensity deviation, is the external temperature deviation, and are the deviations of the excitation voltages of the synchronous motor and synchronous generator respectively; Among them, the interference model follows the constraints introduced by the synchronous machine, the photovoltaic system and the connection between the two; the constraints brought by the synchronous machine include: the power angle constraints of the synchronous machine, the synchronous generator and the synchronous motor, the motion constraints of the synchronous machine, the synchronous generator and the synchronous motor, and the power loss constraints of the synchronous machine; the constraints brought by the photovoltaic system adopt the photovoltaic system operation state equation; the constraints introduced by the connection between the two include: the inverter output and the stator side winding current constraints of the synchronous motor, the power balance constraints after the photovoltaic system is connected to the synchronous machine, and the speed and grid frequency constraints after the photovoltaic system is connected to the synchronous machine; Solve the eigenvalues ​​and eigenvectors of the system matrix A of the interference model, obtain the oscillation mode based on the eigenvector, obtain the damping ratio based on the eigenvector, and optimize the deviation of the excitation voltage of the synchronous motor and the synchronous generator with the goal of minimizing the difference between the damping ratio of each oscillation mode and the reference damping ratio; The objective function is as follows: ,in, is the first The damping ratio of the oscillation mode is For the a reference damping ratio of an oscillation mode, wherein the reference damping ratio meets the oscillation suppression requirement, is the total number of oscillation modes.

[0005] Furthermore, the disturbance model follows the power angle constraints of synchronous machines, synchronous generators and synchronous motors: and synchronous generator Corresponding power angle Hegong Angle After linearization, the following constraints are satisfied: ; in, is the synchronous motor power angle deviation, is the synchronous generator power angle deviation. Based on the active power control method of the source-grid phase difference, the active power transmitted by the synchronous machine increases with the increase of the source-grid phase difference. Under the premise of ignoring the rotor position difference between the synchronous motor and the synchronous generator, that is, =0, then , will soon Defined as the power angle of the synchronous machine, is the synchronous machine power angle deviation.

[0006] Furthermore, the perturbation model follows the motion constraints of synchronous machines, synchronous generators and synchronous motors: In the motion constraint, the synchronous machine rotor motion equation is obtained by superimposing the motion equations of the synchronous generator and the synchronous motor, which can be expressed as: ; ; Where: is the inertia time constant of the synchronous motor and synchronous generator in the synchronous machine, is the deviation of the electromagnetic torque of the synchronous motor, is the deviation of the electromagnetic torque of the synchronous generator, is the damping coefficient of the synchronous motor, is the damping coefficient of the synchronous generator.

[0007] Furthermore, the disturbance model follows the power loss constraint of the synchronous machine. Under the per-unit value, the power loss constraint of the synchronous machine during rotation is expressed as: , Where: is the mechanical loss during the rotation of the synchronous machine system, , is the electromagnetic torque of the synchronous motor, is the electromagnetic torque of the synchronous generator; Linearizing the power loss relationship yields: ; Among them, under the control of the synchronous motor excitation system and the synchronous generator excitation system, the electromagnetic torque deviation of the synchronous motor and the synchronous generator of the synchronous machine is expressed as follows: , ; Where: and are the excitation flux deviations of synchronous motor and synchronous generator respectively; , , , They represent constants related to the parameters and initial conditions of the synchronous motor and synchronous generator respectively.

[0008] Furthermore, the constraints imposed by the photovoltaic system are expressed using the photovoltaic system operating state equation as follows: , , , Where: is the state variable of the photovoltaic system operation state equation, It is the input variable of the state equation of the photovoltaic system operation; middle, is the deviation of the DC side capacitor voltage, and are the deviations of the d-axis and q-axis components of the inverter output current, and is the deviation of the d-axis and q-axis components of the inverter output voltage, , , It is the internal state variable of the controller; middle, is the external light intensity deviation, is the external temperature deviation, and They are the deviations of the d-axis and q-axis components of the grid-side voltage and current, respectively.

[0009] Furthermore, the disturbance model follows the inverter output and synchronous motor stator winding current constraints: When the photovoltaic system is connected to the synchronous machine, the outlet side of the photovoltaic inverter is connected to the stator side winding of the synchronous motor through the filter inductor. The d-axis and q-axis components of the current on the outlet side of the photovoltaic inverter are , The d and q axis input currents of the synchronous motor stator side , equal: , , where the current deviation power angle and flux linkage of the synchronous motor stator side in the synchronous machine are expressed as follows: , , That is, in the interference model, the deviation of the d-axis and q-axis components of the current at the outlet of the photovoltaic inverter is , Power angle deviation of synchronous machine Deviation from synchronous motor excitation flux Alternative.

[0010] Furthermore, the interference model follows the power balance constraint after the PV system is connected to the synchronous machine: Ignoring the active power loss of the filter inductor, the electromagnetic input power of the synchronous motor is equal to the active power on the outlet side of the PV inverter, expressed as: , Where: , are the initial values ​​of the q-axis voltage and current on the inverter port side, , is the deviation of the q-axis voltage and current on the inverter port side; the deviation of the electromagnetic torque of the interference model synchronous motor Deviation of q-axis voltage and current on the inverter port side and Alternative.

[0011] Furthermore, the interference model follows the speed and grid frequency constraints after the PV system is connected to the synchronous machine: after the PV system is connected to the grid through the synchronous machine, the rotor speed is coupled with the grid frequency, which is the synchronous machine rotor angular velocity With reference grid angular frequency Equal, the interference model needs to add the synchronous machine rotor angular velocity deviation compared with the photovoltaic system operation state equation is the coefficient term of the state variable.

[0012] In a second aspect, the present invention provides a photovoltaic system grid-connected oscillation control device via a synchronous machine, comprising: a photovoltaic system and a synchronous machine, the photovoltaic system comprising a photovoltaic module, a DC side voltage-stabilizing capacitor, an inverter, a filter circuit and a controller, the synchronous machine being connected in series to a filter inductor circuit connected to the photovoltaic inverter; a synchronous motor excitation system is configured for the synchronous motor in the synchronous machine, and a synchronous generator excitation system is configured for the synchronous generator in the synchronous machine, the controller comprising at least one processing unit, the processing unit, a storage unit and a collection unit being interconnected through a bus unit, the storage unit storing a computer program and data collected by the collection unit, and when the computer program is executed by the processing unit, the photovoltaic system grid-connected oscillation control method via a synchronous machine is implemented.

[0013] In a third aspect, the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for controlling the oscillation of a photovoltaic system connected to the grid via a synchronous machine is implemented.

[0014] The above technical solution provided by the embodiment of the present invention has the following advantages compared with the prior art: The present application configures a synchronous motor excitation system for the synchronous motor in the synchronous machine, and configures a synchronous generator excitation system for the synchronous generator in the synchronous machine; performs interference modeling on the circuit of the photovoltaic system connected to the grid through the synchronous machine to obtain an interference model; the interference model follows the constraints introduced by the synchronous machine, the photovoltaic system and the connection relationship between the two; the constraints brought by the synchronous machine include: the power angle constraints of the synchronous machine, the synchronous generator and the synchronous motor, the motion constraints of the synchronous machine, the synchronous generator and the synchronous motor, and the power loss constraints of the synchronous machine; the constraints brought by the photovoltaic system adopt the photovoltaic system operation state equation; the constraints introduced by the connection relationship between the two include: the inverter output and the stator side winding current constraints of the synchronous motor, the power balance constraints after the photovoltaic system is connected to the synchronous machine, and the speed and grid frequency constraints after the photovoltaic system is connected to the synchronous machine. Solve the eigenvalue of the system matrix A of the interference model, obtain the oscillation mode based on the eigenvalue, and optimize the deviation of the excitation voltage of the synchronous motor and the synchronous generator with the goal of minimizing the difference between the damping ratio of each oscillation mode and the reference damping ratio. Support better control of oscillations of different vibration modes. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0017] Figure 1 A flow chart of a photovoltaic system grid-connected oscillation control method via a synchronous machine provided by an embodiment of the present invention; Figure 2 A schematic diagram of a device for improving synchronous oscillation of a new energy synchronous machine provided by an embodiment of the present invention; Figure 3 Synchronous motor in a synchronous machine provided by an embodiment of the present invention and synchronous generator Schematic diagram of the power-angle relationship. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0020] Example 1 See also Figure 1 As shown, the technology of the present invention realizes a photovoltaic system grid-connected oscillation control method via a synchronous machine, including: like Figure 2 As shown, the present application configures a synchronous motor excitation system for the synchronous motor in the synchronous machine, and configures a synchronous generator excitation system for the synchronous generator in the synchronous machine, and adjusts the electrical damping of the synchronous machine through the synchronous motor excitation system and the synchronous generator excitation system to maintain the grid voltage stability. After the synchronous machine is connected in series to the filter inductor circuit connected to the photovoltaic inverter, the synchronous motor excitation system and the synchronous generator excitation system respectively apply excitation control to the synchronous motor and the synchronous generator, and adopts PQ decoupled vector control to achieve stable transmission of active power through effective control of the q-axis current.

[0021] In order to achieve grid-connected stability, the present application performs interference modeling on the circuit of the photovoltaic system connected to the grid via a synchronous machine to obtain an interference model.

[0022] The disturbance model follows the constraints introduced by the synchronous machine, the photovoltaic system and the connection relationship between the two.

[0023] The constraints imposed by synchronous machines are as follows: The disturbance model follows the power angle constraints of synchronous machines, synchronous generators and synchronous motors.

[0024] In the specific implementation process, the synchronous motor in the synchronous machine and synchronous generator The power angle relationship is as follows Figure 3 shown. Figure 3 middle is the synchronous motor terminal voltage, is the internal potential of the synchronous motor, is the synchronous generator terminal voltage, is the internal potential of the synchronous generator, is the synchronous motor power angle, is the synchronous generator power angle, is the phase difference between the synchronous motor and synchronous generator terminal voltage, is the rotor position difference between the two motors. Synchronous Motor and synchronous generator Corresponding power angle Hegong Angle After linearization, the following constraints are satisfied: ; in, is the synchronous motor power angle deviation, is the synchronous generator power angle deviation, based on the active power control method of the source-grid phase difference, the active power transmitted by the synchronous machine increases with the increase of the source-grid phase difference. Under the premise of ignoring the rotor position difference between the synchronous motor and the synchronous generator, that is, =0, then , will soon Defined as the power angle of the synchronous machine, the power angle deviation of the synchronous machine As the state variable of the disturbance model, and .

[0025] The perturbation model follows the motion constraints of synchronous machines, synchronous generators, and synchronous motors.

[0026] In the specific implementation process, the synchronous generator and the synchronous motor in the synchronous machine are of the same structure. The synchronous motor is coaxially connected to the synchronous generator, and the mechanical torque and rotor speed are the same. Therefore, in the motion constraint, the synchronous machine rotor motion equation is obtained by superimposing the motion equations of the synchronous generator and the synchronous motor, which is expressed as: ; ; Where: is the speed deviation, is the inertia time constant of the synchronous motor and synchronous generator in the synchronous machine, is the deviation of the electromagnetic torque of the synchronous motor, is the deviation of the electromagnetic torque of the synchronous generator, is the damping coefficient of the synchronous motor, is the damping coefficient of the synchronous generator.

[0027] The disturbance model follows the power loss constraints of the synchronous machine.

[0028] In the specific implementation process, under the per-unit value, the power loss constraint of the synchronous machine during the rotation process is expressed as: ; Where: is the mechanical loss during the rotation of the synchronous machine system, . is the electromagnetic torque of the synchronous motor, is the electromagnetic torque of the synchronous generator.

[0029] Linearizing the power loss relationship yields: , Among them, under the control of the synchronous motor excitation system and the synchronous generator excitation system, the electromagnetic torque deviation of the synchronous motor and the synchronous generator of the synchronous machine is expressed as follows: , ; Where: and are the excitation flux deviations of synchronous motor and synchronous generator respectively; , , , They represent constants related to the parameters and initial conditions of the synchronous motor and synchronous generator respectively.

[0030] and are the d-axis and q-axis components of the initial magnetic flux of the synchronous motor.

[0031] Based on the power angle constraint, motion constraint, and power loss constraint, the synchronous machine power angle deviation The dynamic differential equation of is expressed as: ; The synchronous machine power angle deviation From the dynamic differential equation, we can know that the power angle deviation The dynamic differential equations include and The differential form of shows that the change of the excitation flux of the synchronous motor and synchronous generator will affect the power angle of the synchronous machine. and As the state variable of the disturbance model, and The linearized differential equation is as follows: , , Where: and are the deviations of the excitation voltages of the synchronous motor and synchronous generator, respectively. The coefficients L with different subscripts represent constants related to the parameters of the synchronous motor and synchronous generator.

[0032] Thus, we obtained , , and is the state variable, , , is a disturbance model for a portion of the input variables that depends on the synchronous machine.

[0033] The photovoltaic system includes photovoltaic modules, DC side voltage stabilizing capacitors, inverters, filter circuits and controllers. The constraints brought by the photovoltaic system are expressed by the photovoltaic system operating state equation as follows: , , , Where: is the state variable of the photovoltaic system operation state equation, It is the input variable of the state equation of the photovoltaic system operation; middle, is the deviation of the DC side capacitor voltage, and are the deviations of the d-axis and q-axis components of the inverter output current, and is the deviation of the d-axis and q-axis components of the inverter output voltage, , , It is the internal state variable of the controller; middle, is the external light intensity deviation, is the external temperature deviation, and They are the deviations of the d-axis and q-axis components of the grid-side voltage and current, respectively.

[0034] The interference model follows the electrical connection constraints of the PV system and the synchronous machine, including: The disturbance model follows the inverter output and synchronous motor stator-side winding current constraints: Specifically, when the photovoltaic system is connected to the synchronous machine, the outlet side of the photovoltaic inverter is connected to the stator winding of the synchronous motor through the filter inductor, and the d-axis and q-axis components of the current on the outlet side of the photovoltaic inverter are , The d and q axis input currents of the synchronous motor stator side , equal: , Among them, the current deviation power angle and flux linkage of the synchronous motor stator side in the synchronous machine are expressed as follows: , .

[0035] That is: the deviation of the d-axis and q-axis components of the current at the outlet of the photovoltaic inverter , Using state variables and Alternative.

[0036] The interference model follows the power balance constraint after the photovoltaic system is connected to the synchronous machine: Specifically, ignoring the active power loss of the filter inductor, the electromagnetic input power of the synchronous motor is equal to the active power on the outlet side of the photovoltaic inverter, which is expressed as: , Where: , are the initial values ​​of the q-axis voltage and current on the inverter port side, , is the deviation of the q-axis voltage and current on the inverter port side. It can be seen from this that the deviation of the electromagnetic torque of the synchronous motor use and Alternative.

[0037] The interference model follows the speed and grid frequency constraints after the photovoltaic system is connected to the synchronous machine: Specifically, after the photovoltaic system is connected to the grid through the synchronous machine, the rotor speed is coupled with the grid frequency, which is formally expressed as the synchronous machine rotor angular velocity With reference grid angular frequency Therefore, the synchronous machine rotor angular velocity deviation needs to be added to the original photovoltaic system operating state equation is the coefficient term of the state variable.

[0038] In summary, the interference model is as follows:

[0039]

[0040] Among them, ∆x is the state variable of the disturbance model, ∆u is the input variable of the disturbance model, A is the disturbance model system matrix, and B is the input matrix.

[0041] The eigenvalues ​​and eigenvectors of the system matrix A of the interference model are solved, the oscillation mode is obtained based on the eigenvector, the damping ratio is obtained based on the eigenvector, and the deviation of the excitation voltage of the synchronous motor and the synchronous generator is optimized with the goal of minimizing the difference between the damping ratio of each oscillation mode and the reference damping ratio.

[0042] The objective function is as follows: ,in, is the first The damping ratio of the oscillation mode is For the a reference damping ratio of an oscillation mode, wherein the reference damping ratio meets the oscillation suppression requirement, is the total number of oscillation modes.

[0043] In the specific implementation process, the eigenvalue of the system matrix A is in complex form, the real part of the eigenvalue represents the damping, and the imaginary part of the eigenvalue represents the oscillation frequency. The ratio of the real part to the imaginary part is the damping ratio. The eigenvector corresponding to the eigenvalue describes the oscillation mode of the state variable of the photovoltaic system connected to the grid through the synchronous machine, and how the state variable in the photovoltaic system connected to the grid through the synchronous machine oscillates at a specific frequency.

[0044] Example 2 See also Figure 2 As shown, an embodiment of the present invention provides a photovoltaic system grid-connected oscillation control device via a synchronous machine, comprising: a photovoltaic system and a synchronous machine, the photovoltaic system comprising a photovoltaic module, a DC side voltage stabilizing capacitor, an inverter, a filter circuit and a controller, the synchronous machine is connected in series to the filter inductor circuit connected to the photovoltaic inverter; a synchronous motor excitation system is configured for the synchronous motor in the synchronous machine, and a synchronous generator excitation system is configured for the synchronous generator in the synchronous machine, the controller comprises at least one processing unit, the processing unit, the storage unit and the acquisition unit are interconnected through a bus unit, the storage unit stores a computer program and data collected by the acquisition unit, and when the computer program is executed by the processing unit, the photovoltaic system grid-connected oscillation control method via the synchronous machine is implemented, comprising: A synchronous motor excitation system is configured for the synchronous motor in the synchronous machine, and a synchronous generator excitation system is configured for the synchronous generator in the synchronous machine; The interference model of the photovoltaic system connected to the grid through the synchronous machine is obtained by interference modeling as follows: , , , Among them, ∆x is the state variable of the disturbance model, ∆u is the input variable of the disturbance model, A is the disturbance model system matrix, B is the input matrix, is the deviation of the DC side capacitor voltage, and are the deviations of the d-axis and q-axis components of the inverter output voltage, , , is the controller internal state variable, is the power angle deviation of the synchronous machine, is the synchronous machine rotor angular velocity deviation, and are the excitation flux deviations of synchronous motor and synchronous generator respectively, is the external light intensity deviation, is the external temperature deviation, and are the deviations of the excitation voltages of the synchronous motor and synchronous generator respectively; Among them, the interference model follows the constraints introduced by the synchronous machine, the photovoltaic system and the connection between the two; the constraints brought by the synchronous machine include: the power angle constraints of the synchronous machine, the synchronous generator and the synchronous motor, the motion constraints of the synchronous machine, the synchronous generator and the synchronous motor, and the power loss constraints of the synchronous machine; the constraints brought by the photovoltaic system adopt the photovoltaic system operation state equation; the constraints introduced by the connection between the two include: the inverter output and the stator side winding current constraints of the synchronous motor, the power balance constraints after the photovoltaic system is connected to the synchronous machine, and the speed and grid frequency constraints after the photovoltaic system is connected to the synchronous machine; The eigenvalues ​​of the system matrix A of the interference model are solved, and the oscillation modes are obtained based on the eigenvalues. The deviation of the excitation voltage of the synchronous motor and the synchronous generator is optimized with the goal of minimizing the difference between the damping ratio of each oscillation mode and the reference damping ratio.

[0045] Of course, the computer program stored in the storage unit of the device for improving synchronous oscillation of a new energy synchronous machine provided in an embodiment of the present invention is not limited to the method operations described above, but can also execute related operations in the method for controlling oscillation of a photovoltaic system connected to the grid via a synchronous machine provided in any embodiment of the present invention.

[0046] Example 3 An embodiment of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program. When the computer program is executed, the photovoltaic system grid-connected oscillation control method via a synchronous machine is implemented, including: A synchronous motor excitation system is configured for the synchronous motor in the synchronous machine, and a synchronous generator excitation system is configured for the synchronous generator in the synchronous machine; The interference model of the photovoltaic system connected to the grid through the synchronous machine is obtained by interference modeling as follows: , , , Among them, ∆x is the state variable of the disturbance model, ∆u is the input variable of the disturbance model, A is the disturbance model system matrix, B is the input matrix, is the deviation of the DC side capacitor voltage, and are the deviations of the d-axis and q-axis components of the inverter output voltage, , , is the controller internal state variable, is the power angle deviation of the synchronous machine, is the synchronous machine rotor angular velocity deviation, and are the excitation flux deviations of synchronous motor and synchronous generator respectively, is the external light intensity deviation, is the external temperature deviation, and are the deviations of the excitation voltages of the synchronous motor and synchronous generator respectively; Among them, the interference model follows the constraints introduced by the synchronous machine, the photovoltaic system and the connection between the two; the constraints brought by the synchronous machine include: the power angle constraints of the synchronous machine, the synchronous generator and the synchronous motor, the motion constraints of the synchronous machine, the synchronous generator and the synchronous motor, and the power loss constraints of the synchronous machine; the constraints brought by the photovoltaic system adopt the photovoltaic system operation state equation; the constraints introduced by the connection between the two include: the inverter output and the stator side winding current constraints of the synchronous motor, the power balance constraints after the photovoltaic system is connected to the synchronous machine, and the speed and grid frequency constraints after the photovoltaic system is connected to the synchronous machine; The eigenvalues ​​of the system matrix A of the interference model are solved, and the oscillation modes are obtained based on the eigenvalues. The deviation of the excitation voltage of the synchronous motor and the synchronous generator is optimized with the goal of minimizing the difference between the damping ratio of each oscillation mode and the reference damping ratio.

[0047] A computer-readable storage medium provided in an embodiment of the present invention stores a computer program which is not limited to the method operations described above, but can also execute related operations in a photovoltaic system grid-connected oscillation control method via a synchronous machine provided in any embodiment of the present invention.

[0048] In the embodiments provided by the present invention, it should be understood that the disclosed structures and methods can be implemented in other ways. For example, the structural embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, structures or units, which can be electrical, mechanical or other forms.

[0049] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0050] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0051] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A photovoltaic system grid-connected oscillation control method via a synchronous machine, characterized in that: include: A synchronous motor excitation system is configured for the synchronous motor in the synchronous machine, and a synchronous generator excitation system is configured for the synchronous generator in the synchronous machine; The interference model of the photovoltaic system connected to the grid through the synchronous machine is obtained by interference modeling as follows: ， ， ， Among them, ∆x is the state variable of the disturbance model, ∆u is the input variable of the disturbance model, A is the disturbance model system matrix, B is the input matrix, is the deviation of the DC side capacitor voltage, and are the deviations of the d-axis and q-axis components of the inverter output voltage, , , is the controller internal state variable, is the power angle deviation of the synchronous machine, is the synchronous machine rotor angular velocity deviation, and are the excitation flux deviations of synchronous motor and synchronous generator respectively, is the external light intensity deviation, is the external temperature deviation, and are the deviations of the excitation voltages of the synchronous motor and synchronous generator respectively; Among them, the interference model follows the constraints introduced by the synchronous machine, the photovoltaic system and the connection between the two; the constraints brought by the synchronous machine include: the power angle constraints of the synchronous machine, the synchronous generator and the synchronous motor, the motion constraints of the synchronous machine, the synchronous generator and the synchronous motor, and the power loss constraints of the synchronous machine; the constraints brought by the photovoltaic system adopt the photovoltaic system operation state equation; the constraints introduced by the connection between the two include: the inverter output and the stator side winding current constraints of the synchronous motor, the power balance constraints after the photovoltaic system is connected to the synchronous machine, and the speed and grid frequency constraints after the photovoltaic system is connected to the synchronous machine; Solve the eigenvalues ​​and eigenvectors of the system matrix A of the interference model, obtain the oscillation mode based on the eigenvector, obtain the damping ratio based on the eigenvector, and optimize the deviation of the excitation voltage of the synchronous motor and the synchronous generator with the goal of minimizing the difference between the damping ratio of each oscillation mode and the reference damping ratio; The objective function is as follows: ,in, is the first The damping ratio of the oscillation mode is For the a reference damping ratio of an oscillation mode, wherein the reference damping ratio meets the oscillation suppression requirement, is the total number of oscillation modes.

2. The photovoltaic system grid-connected oscillation control method via a synchronous machine according to claim 1, characterized in that: The disturbance model follows the power angle constraints of synchronous machines, synchronous generators and synchronous motors: Synchronous motors and synchronous generator Corresponding power angle Hegong Angle After linearization, the following constraints are satisfied: ； in, is the synchronous motor power angle deviation, is the synchronous generator power angle deviation. Based on the active power control method of the source-grid phase difference, the active power transmitted by the synchronous machine increases with the increase of the source-grid phase difference. Under the premise of ignoring the rotor position difference between the synchronous motor and the synchronous generator, that is, =0, then , will soon Defined as the power angle of the synchronous machine, is the synchronous machine power angle deviation.

3. The photovoltaic system grid-connected oscillation control method via a synchronous machine according to claim 1, characterized in that: The perturbation model follows the motion constraints for synchronous machines, synchronous generators, and synchronous motors: In the motion constraint, the synchronous machine rotor motion equation is obtained by superimposing the motion equations of the synchronous generator and the synchronous motor, which can be expressed as: ； ； Where: is the inertia time constant of the synchronous motor and synchronous generator in the synchronous machine, is the deviation of the electromagnetic torque of the synchronous motor, is the deviation of the electromagnetic torque of the synchronous generator, is the damping coefficient of the synchronous motor, is the damping coefficient of the synchronous generator.

4. The photovoltaic system grid-connected oscillation control method via a synchronous machine according to claim 1, characterized in that: The disturbance model follows the power loss constraint of the synchronous machine. Under the per-unit value, the power loss constraint of the synchronous machine during rotation is expressed as: ， Where: is the mechanical loss during the rotation of the synchronous machine system, , is the electromagnetic torque of the synchronous motor, is the electromagnetic torque of the synchronous generator; Linearizing the power loss relationship yields: ; Among them, under the control of the synchronous motor excitation system and the synchronous generator excitation system, the electromagnetic torque deviation of the synchronous motor and the synchronous generator of the synchronous machine is expressed as follows: ， ； Where: and are the excitation flux deviations of synchronous motor and synchronous generator respectively; , , , They represent constants related to the parameters and initial conditions of the synchronous motor and synchronous generator respectively.

5. The photovoltaic system grid-connected oscillation control method via synchronous machine according to claim 1, characterized in that: The constraints brought by the photovoltaic system are expressed by the photovoltaic system operation state equation: ， ， ， Where: is the state variable of the photovoltaic system operation state equation, It is the input variable of the state equation of the photovoltaic system operation; middle, is the deviation of the DC side capacitor voltage, and are the deviations of the d-axis and q-axis components of the inverter output current, and is the deviation of the d-axis and q-axis components of the inverter output voltage, , , It is the internal state variable of the controller; middle, is the external light intensity deviation, is the external temperature deviation, and They are the deviations of the d-axis and q-axis components of the grid-side voltage and current, respectively.

6. The photovoltaic system grid-connected oscillation control method via a synchronous machine according to claim 1, characterized in that: The disturbance model follows the inverter output and synchronous motor stator-side winding current constraints: When the photovoltaic system is connected to the synchronous machine, the outlet side of the photovoltaic inverter is connected to the stator side winding of the synchronous motor through the filter inductor. The d-axis and q-axis components of the current on the outlet side of the photovoltaic inverter are , The d and q axis input currents of the synchronous motor stator side , equal: , , where the current deviation power angle and flux linkage of the synchronous motor stator side in the synchronous machine are expressed as follows: ， ， That is, in the interference model, the deviation of the d-axis and q-axis components of the current at the outlet of the photovoltaic inverter is , Power angle deviation of synchronous machine Deviation from synchronous motor excitation flux Alternative.

7. The photovoltaic system grid-connected oscillation control method via a synchronous machine according to claim 1, characterized in that: The interference model follows the power balance constraint after the photovoltaic system is connected to the synchronous machine: Ignoring the active power loss of the filter inductor, the electromagnetic input power of the synchronous motor is equal to the active power on the outlet side of the photovoltaic inverter, which can be expressed as: ， Where: , are the initial values ​​of the q-axis voltage and current on the inverter port side, , is the deviation of the q-axis voltage and current on the inverter port side; the deviation of the electromagnetic torque of the synchronous motor in the interference model Deviation of q-axis voltage and current on the inverter port side and Alternative.

8. The photovoltaic system grid-connected oscillation control method via a synchronous machine according to claim 1, characterized in that: The interference model follows the speed and grid frequency constraints after the photovoltaic system is connected to the synchronous machine: After the photovoltaic system is connected to the grid through the synchronous machine, the rotor speed is coupled with the grid frequency, which is the synchronous machine rotor angular velocity With reference grid angular frequency Equal, the interference model needs to add the synchronous machine rotor angular velocity deviation compared with the photovoltaic system operation state equation is the coefficient term of the state variable.

9. A photovoltaic system grid-connected oscillation control device via a synchronous machine, comprising: A photovoltaic system and a synchronous machine, wherein the photovoltaic system comprises a photovoltaic module, a DC side voltage-stabilizing capacitor, an inverter, a filter circuit and a controller, wherein the synchronous machine is connected in series to the filter inductor circuit connected to the photovoltaic inverter; wherein a synchronous motor excitation system is configured for the synchronous motor in the synchronous machine, and a synchronous generator excitation system is configured for the synchronous generator in the synchronous machine, wherein the controller comprises at least one processing unit, wherein the processing unit, the storage unit and the acquisition unit are interconnected through a bus unit, wherein the storage unit stores a computer program and data collected by the acquisition unit, and wherein when the computer program is executed by the processing unit, the photovoltaic system grid-connected oscillation control method via a synchronous machine as described in any one of claims 1 to 8 is implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the photovoltaic system grid-connected oscillation control method via a synchronous machine as described in any one of claims 1-8 is implemented.

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