General network-side converter network construction control method and system

Abstract

The invention discloses a general network-side converter network construction control method and system, and relates to the technical field of grid-connected inverter control, and the method comprises the steps: collecting the data of a network-side converter, and carrying out the preprocessing; calculating the power angle of the output internal potential based on the preprocessed data; calculating the amplitude of the output internal potential based on the preprocessed data; and obtaining an internal potential vector based on the power angle and amplitude of the internal potential. According to the invention, the DC bus capacitor is directly used as an energy buffer element in the power grid synchronization process, and a simpler and more direct mathematical relation between DC voltage change and internal potential is established, so that the complexity of a control system is reduced, and the stability is easier to control. According to the converter self-synchronization control, when transient power imbalance disturbance occurs in the system, the angle, the frequency and the amplitude of the internal potential can be maintained not to suddenly change, so that the system is transited to a stable state as soon as possible, and the power grid range influenced by faults is narrowed.

Description

Technical Field

[0001] The present invention relates to the technical field of grid-connected inverter control, and in particular to a universal grid-side converter networking control method and system. Background Art

[0002] At present, power electronic equipment such as wind power generally uses a grid-following control method based on phase-locked synchronization, and the phase-locked loop is usually designed with a fast dynamic response. When the system faces a large disturbance, the phase-locked loop will quickly drive the internal potential phase change to achieve synchronous operation with the grid, and it cannot use the kinetic energy stored in the rotor to support the grid to suppress frequency fluctuations like traditional synchronous generators.

[0003] At the same time, under the vector control based on phase-locked synchronization, the amplitude / phase formation of the potential inside the unit is complex, and the relationship between power change and internal potential reflects high-order, nonlinear characteristics. With the increase in the proportion of new energy, the strength of power electronic equipment access to the system becomes relatively weak, and the coupling degree between the equipment phase-locked loop and the current loop and other control links deepens, which can easily lead to system oscillation problems involving power electronic equipment. Summary of the invention

[0004] In view of the above-mentioned problems, the present invention is proposed.

[0005] Therefore, the technical problem solved by the present invention is: the conventional grid-side converter networking control strategy requires the addition of a stabilizer to achieve a wide short-circuit ratio operating range. This method can adapt to wide short-circuit ratio operating scenarios without the need to add a stabilizer, thereby improving the adaptability of the grid-type converter to the grid strength.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a general grid-side converter network control method, which comprises the following steps:

[0007] Collect grid-side converter data and perform preprocessing;

[0008] Calculate the power angle of the output internal potential based on the preprocessed data;

[0009] Calculate the amplitude of the output internal potential based on the preprocessed data;

[0010] The internal potential vector is obtained based on the power angle and magnitude of the internal potential.

[0011] As a preferred solution of a universal grid-side converter network control method described in the present invention, wherein: the grid-side converter data includes DC voltage, three-phase AC voltage at the grid connection point, and three-phase AC current at the grid connection point;

[0012] The preprocessing is to calculate the positive sequence voltage modulus U of the grid connection point by the three-phase AC voltage of the grid connection point. mThe grid-connected point output reactive power Q is calculated from the grid-connected point three-phase AC voltage and grid-connected point three-phase AC current.

[0013] As a preferred solution of a universal grid-side converter network control method described in the present invention, the internal potential power angle is based on preprocessed data, and the DC voltage command U dcref With DC voltage U dc By making a difference, the power angle deviation Δθ is obtained through the proportional integral link, and the angular frequency ω is set. 0 , the phase angle θ at the set angular frequency is obtained by integration 0 , the power angle deviation Δθ and the phase angle θ at the set angular frequency 0 The internal potential angle θ is obtained by superposition.

[0014] As a preferred solution of a universal grid-side converter network control method described in the present invention, the amplitude of the internal potential is based on the preprocessed data, and the reactive power instruction Q ref Subtract the reactive power Q and obtain the internal potential amplitude deviation ΔE through the proportional integral link. 1 ; Set the positive sequence voltage modulus value instruction U mref The positive sequence voltage modulus U m The internal potential amplitude deviation ΔE is obtained through the proportional integral link. 2 ; Select the internal potential amplitude deviation ΔE according to the grid demand 1 or ΔE 2 , and the initial value of the internal potential voltage E 0 The internal potential amplitude E is obtained by superposition.

[0015] As a preferred solution of a universal grid-side converter network control method described in the present invention, wherein: the internal potential is the final internal potential obtained by synthesizing the internal potential power angle θ and the internal potential amplitude E through a vector synthesis link.

[0016] Another object of the present invention is to provide a universal grid-side converter networking control system, which can adapt to wide short-circuit ratio operation scenarios without adding a stabilizer, thereby improving the converter's adaptability to grid strength and solving the problem that conventional grid-side converter networking control strategies cannot achieve a wide short-circuit ratio operating range.

[0017] In order to solve the above technical problems, the present invention provides the following technical solutions: A universal grid-side converter network control system, comprising: a first module, a second module, a third module and a fourth module;

[0018] The first module is to obtain the DC voltage U dc , reactive power Q and grid-connected point positive sequence voltage modulus U m ;

[0019] The second module is a calculation module of the internal potential power angle θ;

[0020] The third module is a calculation module of the internal potential amplitude E;

[0021] The fourth module is a module for calculating the internal potential.

[0022] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of a general grid-side converter networking control method as described above are implemented.

[0023] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of a general grid-side converter networking control method as described above.

[0024] Beneficial effects of the present invention: The present invention directly uses the DC bus capacitor as an energy buffer element in the process of power grid synchronization, and by establishing a simpler and more direct mathematical connection between the DC voltage change and the internal potential, the complexity of the control system is reduced, and the stability is easier to control. The converter self-synchronous control in the present invention can maintain the angle, frequency and amplitude of the internal potential without sudden changes when a transient power imbalance disturbance occurs in the system, so that the system transitions to a stable state as soon as possible, reducing the scope of the power grid affected by the fault. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0026] Figure 1 An overall flow chart of a general grid-side converter network control method provided for the first embodiment of the present invention;

[0027] Figure 2 A structural diagram of a universal grid-side converter network control system provided for a second embodiment of the present invention;

[0028] Figure 3 An equivalent model diagram of a grid-connected inverter connected to an AC power grid in a general grid-side converter grid control method provided in a third embodiment of the present invention;

[0029] Figure 4 A schematic diagram of a general grid-side converter network control method provided for a third embodiment of the present invention;

[0030] Figure 5 A fault ride-through simulation waveform diagram of a universal grid-side converter network control method provided in the third embodiment of the present invention. DETAILED DESCRIPTION

[0031] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0032] Example 1, reference Figure 1 According to an embodiment of the present invention, a general grid-side converter network control method is provided, comprising:

[0033] Collect grid-side converter data and perform preprocessing;

[0034] Calculate the power angle of the output internal potential based on the preprocessed data;

[0035] Calculate the amplitude of the output internal potential based on the preprocessed data;

[0036] The internal potential vector is obtained based on the power angle and magnitude of the internal potential.

[0037] The positive sequence voltage modulus U of the grid connection point is calculated from the three-phase AC voltage of the grid connection point. m The grid-connected point output reactive power Q is calculated from the grid-connected point three-phase AC voltage and grid-connected point three-phase AC current.

[0038] The internal potential power angle is based on the pre-processed data, which converts the DC voltage command U dcref With DC voltage U dc By making a difference, the power angle deviation Δθ is obtained through the proportional integral link, and the angular frequency ω is set. 0 , the phase angle θ at the set angular frequency is obtained by integration 0 , the power angle deviation Δθ and the phase angle θ at the set angular frequency 0 The internal potential angle θ is obtained by superposition.

[0039] The amplitude of the internal potential is based on the preprocessed data, and the reactive power command Q ref Subtract the reactive power Q and obtain the internal potential amplitude deviation ΔE through the proportional integral link. 1 ; Set the positive sequence voltage modulus value instruction U mref The positive sequence voltage modulus U m The internal potential amplitude deviation ΔE is obtained through the proportional integral link. 2 ; Select the internal potential amplitude deviation ΔE according to the grid demand1 or ΔE 2 , and the initial value of the internal potential voltage E 0 The internal potential amplitude E is obtained by superposition.

[0040] The internal potential is obtained by vector synthesis of the internal potential angle θ and the internal potential amplitude E.

[0041] Embodiment 2, Figure 2 As an embodiment of the present invention, a system of a universal grid-side converter network control method is provided, comprising: a first module 100, a second module 200, a third module 300 and a fourth module 400;

[0042] The first module 100 is used to obtain a DC voltage U dc , reactive power Q and grid-connected point positive sequence voltage modulus U m ;

[0043] The second module 200 is a calculation module of the internal potential power angle θ;

[0044] The third module 300 is a calculation module of the internal potential amplitude E;

[0045] The fourth module 400 is a module for calculating the internal potential.

[0046] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program code.

[0047] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0048] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0049] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0050] Example 3, reference Figure 3 to Figure 5 Another embodiment of the present invention, in order to verify the beneficial effects of the present invention, is scientifically demonstrated through economic benefit calculation and simulation experiments. This embodiment experiments the existing traditional method and the method of this embodiment respectively.

[0051] The equivalent model of wind turbines connected to the AC grid is shown in the attached figure. Figure 3 As shown, the grid-connected voltage sampling point of the wind turbine is U, and the outlet voltage of the wind turbine grid-side converter is the internal potential E.

[0052] A general grid-side converter control method includes: obtaining an internal potential power angle θ and an amplitude E, and obtaining an internal potential Ee through a vector synthesis link. jθ .

[0053] As attached Figure 4 As shown, the process of obtaining the internal potential angle θ is to obtain the DC voltage U dc , DC voltage command U dcre f and DC voltage U dc The power angle deviation Δθ is obtained by making a difference through the proportional integral link, and the angular frequency ω is set. 0 The phase angle θ at the set angular frequency is obtained by integration 0 , power angle deviation Δθ and phase angle θ at set angular frequency 0 The internal potential angle θ is obtained by superposition.

[0054] The process of obtaining the internal potential amplitude E is to obtain the reactive power Q and the reactive power command Q ref The internal potential amplitude deviation ΔE is obtained by subtracting the reactive power Q through the proportional integral link. 1 ; Get the positive sequence voltage modulus U of the grid connection point m , grid-connected point positive sequence voltage modulus command U mref The positive sequence voltage modulus U m The internal potential amplitude deviation ΔE is obtained by taking the difference and passing it through the proportional integral link. 2 ; Select the internal potential amplitude deviation ΔE as needed 1 / ΔE 2 , and the initial value of the internal potential voltage E 0 The internal potential amplitude E is obtained by superposition.

[0055] The internal potential Ee is obtained through vector synthesis. jθ The simulation test waveform is as follows: Figure 5 As shown, the grid-side converter network control is adopted, and under the condition of short-circuit ratio of 2, 70% low voltage ride-through is entered at 3s, and the continuous operation state without disconnection from the grid is maintained, and rapid reactive power support is performed, and the impact on the DC voltage is small. It shows that the general grid-side converter network control method proposed in this embodiment has a good practical effect.

[0056] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A general grid-side converter network control method, characterized in that: include: Collect grid-side converter data and perform preprocessing; Calculate the power angle of the output internal potential based on the preprocessed data; Calculate the amplitude of the output internal potential based on the preprocessed data; The internal potential vector is obtained based on the power angle and magnitude of the internal potential.

2. A universal grid-side converter network control method according to claim 1, characterized in that: The grid-side converter data includes DC voltage, three-phase AC voltage at the grid connection point, and three-phase AC current at the grid connection point; The preprocessing is to calculate the positive sequence voltage modulus U of the grid connection point by the three-phase AC voltage of the grid connection point. m The grid-connected point output reactive power Q is calculated from the grid-connected point three-phase AC voltage and grid-connected point three-phase AC current.

3. A universal grid-side converter network control method as claimed in claim 2, characterized in that: The internal potential power angle is based on the pre-processed data, and the DC voltage command U dcref With DC voltage U dc The power angle deviation Δθ is obtained through the proportional integral link, the angular frequency ω0 is set, and the phase angle θ0 at the set angular frequency is obtained by integration. The power angle deviation Δθ and the phase angle θ0 at the set angular frequency are superimposed to obtain the internal potential power angle θ.

4. A universal grid-side converter network control method as claimed in claim 3, characterized in that: The magnitude of the internal potential is based on the preprocessed data, and the reactive power command Q reff Subtract the reactive power Q, and get the internal potential amplitude deviation ΔE1 through the proportional integral link; the positive sequence voltage modulus command U mref The positive sequence voltage modulus U m The internal potential amplitude deviation ΔE2 is obtained by making a difference through a proportional-integral link; the internal potential amplitude deviation ΔE1 or ΔE2 is selected according to the grid demand, and the internal potential amplitude E is obtained by superimposing it with the initial value E0 of the internal potential voltage.

5. A universal grid-side converter network control method as claimed in claim 4, characterized in that: The internal potential is obtained by combining the internal potential angle θ and the internal potential amplitude E through a vector synthesis link to obtain the final internal potential.

6. A system using a universal grid-side converter network control method as claimed in any one of claims 1 to 5, characterized in that: It comprises a first module (100), a second module (200), a third module (300) and a fourth module (400); The first module is to obtain the DC voltage U dc , reactive power Q and grid-connected point positive sequence voltage modulus u m ; The second module is a calculation module of the internal potential power angle θ; The third module is a calculation module of the internal potential amplitude E; The fourth module is a module for calculating the internal potential.

7. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the processor executes the computer program, the processor implements the steps of a general grid-side converter networking control method described in any one of claims 1 to 5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of a general grid-side converter networking control method described in any one of claims 1 to 5 are implemented.

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