Method and device for setting additional control parameters of grid-forming type photovoltaic direct-current voltage

Abstract

The invention provides a network construction type photovoltaic direct current voltage additional control parameter setting method and device, and the method comprises the steps: determining a complex torque model and a complex torque coefficient based on a mathematical model of a network construction type photovoltaic grid-connected system; wherein the mathematical model comprises DC voltage additional control parameters; estimating the dominant oscillation frequency of the system based on the complex torque model and the complex torque coefficient; according to the dominant oscillation frequency and the complex torque coefficient of the system, determining a stability criterion of a DC voltage additional control parameter in the grid-forming photovoltaic grid-connected system; and setting a direct current voltage additional control parameter according to a stability criterion. According to the method, a complex torque model and a complex torque coefficient are calculated according to a mathematical model of a grid-forming type photovoltaic grid-connected system containing a direct-current voltage additional control strategy, and a stable criterion of grid-forming type photovoltaic direct-current voltage additional control parameters is given according to the complex torque model and the complex torque coefficient, so that the direct-current voltage additional control parameters are set, and the stability of the grid-forming type photovoltaic grid-connected system is improved. And proper direct-current voltage additional control parameters are determined, so that stable operation of the network construction type photovoltaic grid-connected system is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of power system operation control, and in particular to a method and device for setting additional control parameters of a grid-connected photovoltaic direct current voltage. Background Art

[0002] As the proportion of power electronic interface power supplies in power systems continues to increase, the safety of system frequency and voltage is seriously threatened. In addition, the risk of power system oscillation is also gradually increasing. In this case, transforming traditional grid-following photovoltaic systems into grid-building photovoltaic systems can effectively improve the stability of the power system.

[0003] Grid-connected photovoltaic systems generally adopt a virtual synchronous machine control strategy, which can simulate the working characteristics of traditional synchronous generators during operation. In actual operation, in order to ensure that the DC voltage of the grid-connected photovoltaic system can remain stable during disturbances, appropriate additional control of the DC voltage is required. However, there is currently a lack of theoretical basis for the setting of additional control parameters for DC voltage. Unreasonable setting of additional DC voltage parameters may lead to unstable operation of the grid-connected photovoltaic system, affecting the overall efficiency and stability of the system.

[0004] Therefore, how to solve the problem that the existing technology lacks a setting solution for the additional parameters of the DC voltage of the grid-connected photovoltaic system, resulting in the inability of the grid-connected photovoltaic system to operate stably, is an important issue that needs to be urgently solved in the field of power system operation and control. Summary of the invention

[0005] The present invention provides a method and device for setting additional control parameters of a grid-type photovoltaic DC voltage, which is used to overcome the defect that there is a lack of setting schemes for additional parameters of the DC voltage of a grid-type photovoltaic system in the prior art, resulting in the inability of the grid-type photovoltaic system to operate stably. Determining appropriate additional control parameters of the DC voltage is helpful for the stable operation of the grid-type photovoltaic grid-connected system.

[0006] On the one hand, the present invention provides a method for setting additional control parameters of a grid-connected photovoltaic DC voltage, comprising: determining a complex torque model and a complex torque coefficient based on a mathematical model of a grid-connected photovoltaic grid-connected system; wherein the mathematical model includes additional control parameters of the DC voltage; estimating the dominant oscillation frequency of the system based on the complex torque model and the complex torque coefficient; determining a stability criterion of the additional control parameters of the DC voltage in the grid-connected photovoltaic grid-connected system according to the dominant oscillation frequency and the complex torque coefficient of the system; and setting the additional control parameters of the DC voltage according to the stability criterion.

[0007] Furthermore, the mathematical model includes a DC voltage and a power angle; accordingly, based on the mathematical model of the grid-connected photovoltaic grid-connected system, a complex torque model and a complex torque coefficient are determined, including: based on the mathematical model, complex torque modeling is performed with the DC voltage and the power angle as the dominant links of the grid-connected photovoltaic grid-connected system to obtain the complex torque model; the mathematical model is simplified and derived to the complex torque model to obtain the complex torque coefficient.

[0008] Furthermore, the complex torque coefficient includes an equivalent damping torque coefficient and an equivalent synchronous torque coefficient; accordingly, based on the complex torque model and the complex torque coefficient, the dominant oscillation frequency of the system is estimated, including: based on the complex torque model, estimating the dominant oscillation frequency of the system when the equivalent damping torque coefficient is approximately zero, and obtaining an expression for the dominant oscillation frequency of the system; scaling the equivalent synchronous torque coefficient, and substituting the scaled equivalent synchronous torque coefficient into the expression for the dominant oscillation frequency of the system, to obtain an estimated dominant oscillation frequency of the system.

[0009] Furthermore, according to the system dominant oscillation frequency and complex torque coefficient, a stability criterion of the additional control parameters of the DC voltage in the grid-connected photovoltaic grid-connected system is determined, including: determining a conditional expression of the equivalent damping torque coefficient; substituting the estimated system dominant oscillation frequency into the conditional expression to obtain the stability criterion.

[0010] Furthermore, the conditional expression is as follows: ; The stability criterion is as follows: ; in, represents the equivalent damping torque coefficient, Indicates the DC voltage additional control integral coefficient, represents the damping coefficient of the virtual synchronous machine, represents the rated angular frequency, Indicates the DC voltage additional control proportional coefficient, represents the DC voltage dynamic equivalent coefficient, represents the synchronous power factor, Indicates the virtual synchronous inertia time constant.

[0011] Furthermore, the mathematical model of the grid-connected photovoltaic system is defined as follows: ; The complex torque model is defined as follows: ; ; ; in, Indicates the inverter output active power, represents the damping coefficient of the virtual synchronous machine, represents the virtual synchronization angular frequency, represents the virtual synchronous inertia time constant, represents the Laplace operator, Indicates the DC voltage additional control proportional coefficient, Indicates the DC voltage additional control integral coefficient, Indicates DC voltage, represents the composite angular frequency, represents the composite power angle, represents the rated angular frequency, Indicates the power base value, represents the DC capacitance, represents the synchronous power factor, represents the potential amplitude in the inverter, Indicates the grid voltage amplitude, Indicates the connection reactance between the inverter and the grid. represents the grid voltage phase angle, represents the equivalent damping torque coefficient, represents the equivalent synchronous torque coefficient, represents the dominant oscillation frequency of the system, Represents the dynamic equivalent coefficient of DC voltage.

[0012] In a second aspect, the present invention also provides a grid-type photovoltaic DC voltage additional control parameter setting device, comprising: a complex torque modeling module, used to determine a complex torque model and a complex torque coefficient based on a mathematical model of a grid-type photovoltaic grid-connected system; wherein the mathematical model includes a DC voltage additional control parameter; a system dominant oscillation frequency estimation module, used to estimate the system dominant oscillation frequency based on the complex torque model and the complex torque coefficient; a stability criterion determination module, used to determine the stability criterion of the DC voltage additional control parameter in the grid-type photovoltaic grid-connected system according to the system dominant oscillation frequency and the complex torque coefficient; a DC voltage additional control parameter setting module, used to set the DC voltage additional control parameter according to the stability criterion.

[0013] In a third aspect, the present invention further provides an electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the method for setting additional control parameters of the grid-connected photovoltaic DC voltage as described in any one of the above-mentioned methods is implemented.

[0014] In a fourth aspect, the present invention further provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements a method for setting additional control parameters of a grid-connected photovoltaic DC voltage as described in any one of the above.

[0015] In a fifth aspect, the present invention further provides a computer program product, comprising a computer program, which, when executed by a processor, implements a method for setting additional control parameters of a grid-connected photovoltaic DC voltage as described in any one of the above.

[0016] The grid-type photovoltaic DC voltage additional control parameter setting method provided by the present invention determines the complex torque model and the complex torque coefficient based on the mathematical model of the grid-type photovoltaic grid-connected system; wherein the mathematical model includes the DC voltage additional control parameter; and based on the complex torque model and the complex torque coefficient, estimates the system dominant oscillation frequency; and then determines the stability criterion of the DC voltage additional control parameter in the grid-type photovoltaic grid-connected system according to the system dominant oscillation frequency and the complex torque coefficient; thus, the DC voltage additional control parameter is set according to the stability criterion. The method calculates the complex torque model and the complex torque coefficient according to the mathematical model of the grid-type photovoltaic grid-connected system containing the DC voltage additional control strategy, and gives the stability criterion of the grid-type photovoltaic DC voltage additional control parameter according to the complex torque model and the complex torque coefficient, thereby setting the DC voltage additional control parameter, determining the appropriate DC voltage additional control parameter, and ensuring the stable operation of the grid-type photovoltaic grid-connected system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a flow chart of a method for setting additional control parameters of a grid-connected photovoltaic DC voltage provided by an embodiment of the present invention.

[0019] Figure 2 It is a structural diagram of a grid-connected photovoltaic active power control loop including a DC voltage additional control strategy provided by an embodiment of the present invention.

[0020] Figure 3 It is a schematic diagram of grid-connected photovoltaic complex torque modeling including a DC voltage additional control strategy provided by an embodiment of the present invention.

[0021] Figure 4 It is a schematic diagram of the overall process of the method for setting additional control parameters of the grid-connected photovoltaic DC voltage provided by an embodiment of the present invention.

[0022] Figure 5 It is a structural schematic diagram of a grid-type photovoltaic DC voltage additional control parameter setting device provided in an embodiment of the present invention.

[0023] Figure 6 It is a schematic diagram of the physical structure of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings 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.

[0025] It should be noted that transforming a grid-connected photovoltaic system into a grid-connected photovoltaic system is helpful to improve the stability of the power system. Furthermore, in order to keep the DC voltage in the grid-connected photovoltaic system stable during disturbances, additional DC voltage control is required. However, there is currently a lack of theoretical basis for setting additional DC voltage control parameters, and inappropriate additional DC voltage control parameters may cause the grid-connected photovoltaic system to be unable to operate stably.

[0026] In view of this, the present invention proposes a method for setting additional control parameters of a grid-connected photovoltaic DC voltage. Specifically, Figure 1 The figure shows a flow chart of a method for setting additional control parameters of a grid-connected photovoltaic DC voltage provided by an embodiment of the present invention.

[0027] like Figure 1 As shown, the method includes: S110, determining a complex torque model and a complex torque coefficient based on a mathematical model of a grid-connected photovoltaic grid-connected system; wherein the mathematical model includes a DC voltage additional control parameter; S120, estimating a system dominant oscillation frequency based on the complex torque model and the complex torque coefficient; S130, determining a stability criterion of a DC voltage additional control parameter in the grid-connected photovoltaic grid-connected system according to the system dominant oscillation frequency and the complex torque coefficient; S140, adjusting the DC voltage additional control parameter according to the stability criterion.

[0028] The following will describe steps S110 - S140 and related steps in detail.

[0029] S110, determining a complex torque model and a complex torque coefficient based on a mathematical model of a grid-connected photovoltaic system; wherein the mathematical model includes a DC voltage additional control parameter.

[0030] Grid-forming PV Grid-connected System is a new type of photovoltaic power system that can actively support grid voltage and frequency, helping to enhance the stability and reliability of the power system.

[0031] It is easy to understand that according to the dynamic characteristics of the grid-connected photovoltaic system, it can be modeled as a corresponding mathematical model. The mathematical model takes into account the changes in power, frequency, voltage and angle, and especially the influence of the DC voltage control strategy.

[0032] In a specific embodiment, the mathematical model obtained by modeling the grid-connected photovoltaic system can be shown in the following formula (1).

[0033] (1).

[0034] In formula (1), Indicates the inverter output active power, represents the damping coefficient of the virtual synchronous machine, represents the virtual synchronization angular frequency, represents the virtual synchronous inertia time constant, represents the Laplace operator, Indicates the DC voltage additional control proportional coefficient, Indicates the DC voltage additional control integral coefficient, Indicates DC voltage, represents the composite angular frequency, represents the composite power angle, represents the rated angular frequency, Indicates the power base value, represents the DC capacitance, represents the synchronous power factor, represents the potential amplitude in the inverter, Indicates the grid voltage amplitude, Indicates the connection reactance between the inverter and the grid. Indicates the grid voltage phase angle.

[0035] Corresponding to the mathematical model, Figure 2 The structure diagram of the grid-connected photovoltaic active power control loop with the additional DC voltage control strategy provided by the embodiment of the present invention is shown, especially corresponding to the first equation and the second equation in the mathematical model (1). Figure 2 middle, , are input signals, Indicates the power reference value, Indicates the DC voltage reference value.

[0036] Then, the DC voltage dynamics (see the fourth equation in the mathematical model) and the power angle dynamics (see the third equation in the mathematical model) are used as the dominant links of the grid-connected photovoltaic grid-connected system with a DC voltage additional control strategy for complex torque modeling, and the corresponding complex torque model can be obtained. By simplifying and deriving the mathematical model to the complex torque model, the complex torque coefficient of the complex torque model can be obtained. The complex torque coefficient here refers to the complex torque coefficient expression, in which the dominant oscillation frequency of the system needs to be further estimated.

[0037] In a specific embodiment, the complex torque model obtained by performing complex torque modeling can be referred to as the following formula (2), and the complex torque coefficient includes an equivalent damping torque coefficient and an equivalent synchronous torque coefficient, which can be specifically referred to as the following formulas (3)-(4).

[0038] (2).

[0039] )(3).

[0040] (4).

[0041] In formulas (2)-(4), , is a real number, represents the equivalent damping torque coefficient, represents the equivalent synchronous torque coefficient, represents the dominant oscillation frequency of the system, Represents the dynamic equivalent coefficient of DC voltage.

[0042] Corresponding to the complex torque model, Figure 3 A schematic diagram of grid-connected photovoltaic complex torque modeling including a DC voltage additional control strategy provided by an embodiment of the present invention is shown.

[0043] Thus, the complex torque model and the corresponding complex torque coefficient can be obtained.

[0044] Further, execute step S120.

[0045] S120: Estimate the dominant oscillation frequency of the system based on the complex torque model and the complex torque coefficient.

[0046] It is easy to understand that according to the complex torque model, in the critical case of approximately zero damping, the equivalent damping torque coefficient , the dominant oscillation frequency of the system can be estimated and the expression of the dominant oscillation frequency of the system can be obtained. For details, please refer to the following formula (5).

[0047] (5).

[0048] By the equivalent synchronous torque coefficient Scaling to get The scaled equivalent synchronous torque coefficient Substituting into the system dominant oscillation frequency expression (5), the estimated system dominant oscillation frequency is obtained, which can be specifically seen in the following equation (6).

[0049] (6).

[0050] After the system dominant oscillation frequency is estimated, step S130 is executed.

[0051] S130, determining a stability criterion of a DC voltage additional control parameter in a grid-connected photovoltaic system according to the dominant oscillation frequency and the complex torque coefficient of the system.

[0052] It is easy to understand that in power systems, especially when it comes to synchronous generators or inverters that simulate the behavior of synchronous generators (such as virtual synchronous machines VSG), the equivalent damping torque coefficient is usually expected to be positive. This is because a positive equivalent damping torque coefficient helps to suppress the oscillation of the system and increase the stability of the system. When a disturbance occurs, a positive equivalent damping torque coefficient can absorb additional energy, help the system return to a stable state faster, and reduce overshoot and oscillation.

[0053] Based on this, in this embodiment, the equivalent damping torque coefficient is greater than 0 ( ) is determined as a conditional expression, and then the estimated system dominant oscillation frequency is substituted into the conditional expression to obtain the stability criterion of the grid-connected photovoltaic DC voltage additional control parameter. The stability criterion can be specifically referred to in the following formula (7).

[0054] (7).

[0055] After determining the stability criterion (7) of the additional control parameters of the DC voltage in the grid-connected photovoltaic system, step S140 is executed.

[0056] S140: adjusting the DC voltage additional control parameter according to the stability criterion.

[0057] It is easy to understand that, on the basis of determining other parameters in the stability criterion except the DC voltage additional control parameter, by adjusting the DC voltage additional control parameter (i.e., the DC voltage additional control integral coefficient and DC voltage additional control proportionality factor ), ensuring that the above stability criterion (7) holds, thereby ensuring the stability of the grid-connected photovoltaic system.

[0058] In this embodiment, a complex torque model and a complex torque coefficient are determined based on a mathematical model of a grid-connected photovoltaic grid-connected system; wherein the mathematical model includes a DC voltage additional control parameter; and based on the complex torque model and the complex torque coefficient, the dominant oscillation frequency of the system is estimated; and then, according to the dominant oscillation frequency of the system and the complex torque coefficient, a stability criterion of the DC voltage additional control parameter in the grid-connected photovoltaic grid-connected system is determined; thus, according to the stability criterion, the DC voltage additional control parameter is adjusted. This method calculates a complex torque model and a complex torque coefficient based on a mathematical model of a grid-connected photovoltaic grid-connected system including a DC voltage additional control strategy, and gives a stability criterion of the grid-connected photovoltaic DC voltage additional control parameter based on the complex torque model and the complex torque coefficient, thereby adjusting the DC voltage additional control parameter, determining appropriate DC voltage additional control parameters, and ensuring the stable operation of the grid-connected photovoltaic grid-connected system.

[0059] In other embodiments, Figure 4 The overall flow chart of the method for setting additional control parameters of the grid-connected photovoltaic DC voltage provided by an embodiment of the present invention is shown.

[0060] like Figure 4 As shown, firstly, based on the mathematical model of the grid-connected photovoltaic grid-connected system, the DC voltage dynamics and the power angle dynamics are used as the leading links of the grid-connected photovoltaic grid-connected system with a DC voltage additional control strategy to perform complex torque modeling, and the complex torque model is obtained. The mathematical model is simplified and derived to the complex torque model to obtain the equivalent damping torque coefficient and the equivalent synchronous torque coefficient.

[0061] Then, according to the complex torque model, the dominant oscillation frequency of the system is estimated when the equivalent damping torque coefficient is approximately zero, and the expression of the dominant oscillation frequency of the system is obtained.

[0062] Next, the equivalent synchronous torque coefficient is scaled, and the scaled equivalent synchronous torque coefficient is substituted into the expression of the system dominant oscillation frequency to obtain the estimated system dominant oscillation frequency.

[0063] Furthermore, the estimated dominant oscillation frequency of the system is substituted into the conditional expression of the equivalent damping torque coefficient, and the stability criterion of the additional control parameters of the grid-connected photovoltaic DC voltage is given.

[0064] Finally, according to the stability criterion of the additional control parameters of the grid-connected photovoltaic DC voltage, the grid-connected photovoltaic DC voltage control parameters are adjusted to ensure the safe and stable operation of the grid-connected photovoltaic grid-connected system.

[0065] Corresponding to the grid-forming photovoltaic DC voltage additional control parameter setting method described in the above embodiments, the present invention also proposes a grid-forming photovoltaic DC voltage additional control parameter setting device.

[0066] Specifically, Figure 5 The schematic diagram of the structure of the additional control parameter setting device for the grid-connected photovoltaic DC voltage provided by the embodiment of the present invention is shown.

[0067] like Figure 5 As shown, the device includes: a complex torque modeling module 510, which is used to determine the complex torque model and the complex torque coefficient based on the mathematical model of the grid-connected photovoltaic grid-connected system; wherein the mathematical model includes a DC voltage additional control parameter; a system dominant oscillation frequency estimation module 520, which is used to estimate the system dominant oscillation frequency based on the complex torque model and the complex torque coefficient; a stability criterion determination module 530, which is used to determine the stability criterion of the DC voltage additional control parameter in the grid-connected photovoltaic grid-connected system according to the system dominant oscillation frequency and the complex torque coefficient; a DC voltage additional control parameter setting module 540, which is used to set the DC voltage additional control parameter according to the stability criterion.

[0068] In this embodiment, the complex torque model and the complex torque coefficient are determined based on the mathematical model of the grid-type photovoltaic grid-connected system by the complex torque modeling module 510; wherein the mathematical model includes the DC voltage additional control parameter; the system dominant oscillation frequency estimation module 520 estimates the system dominant oscillation frequency based on the complex torque model and the complex torque coefficient; and then the stability criterion determination module 530 determines the stability criterion of the DC voltage additional control parameter in the grid-type photovoltaic grid-connected system according to the system dominant oscillation frequency and the complex torque coefficient; thus, the DC voltage additional control parameter setting module 540 sets the DC voltage additional control parameter according to the stability criterion. The device calculates the complex torque model and the complex torque coefficient according to the mathematical model of the grid-type photovoltaic grid-connected system including the DC voltage additional control strategy, and gives the stability criterion of the grid-type photovoltaic DC voltage additional control parameter according to the complex torque model and the complex torque coefficient, thereby setting the DC voltage additional control parameter, determining the appropriate DC voltage additional control parameter, and ensuring the stable operation of the grid-type photovoltaic grid-connected system.

[0069] It should be noted that the grid-type photovoltaic DC voltage additional control parameter setting device provided in the embodiment of the present invention and the grid-type photovoltaic DC voltage additional control parameter setting method described in the above embodiments can correspond to each other and will not be repeated here.

[0070] Figure 6 An example of a physical structure diagram of an electronic device is shown in FIG. Figure 6As shown, the electronic device may include: a processor 610, a communication interface 620, a memory 630 and a communication bus 640, wherein the processor 610, the communication interface 620 and the memory 630 communicate with each other through the communication bus 640. The processor 610 may call the logic instructions in the memory 630 to execute the grid-type photovoltaic DC voltage additional control parameter setting method, the method comprising: determining a complex torque model and a complex torque coefficient based on a mathematical model of a grid-type photovoltaic grid-connected system; wherein the mathematical model includes a DC voltage additional control parameter; estimating a system dominant oscillation frequency based on the complex torque model and the complex torque coefficient; determining a stability criterion of a DC voltage additional control parameter in a grid-type photovoltaic grid-connected system according to the system dominant oscillation frequency and the complex torque coefficient; and setting the DC voltage additional control parameter according to the stability criterion.

[0071] In addition, the logic instructions in the above-mentioned memory 630 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on such an understanding, the technical solution of the present invention, in essence, 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, and the computer software product is stored in a storage medium, including a number of 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. Various media that can store program codes.

[0072] On the other hand, the present invention also provides a computer program product, which includes a computer program, and the computer program can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the grid-type photovoltaic DC voltage additional control parameter adjustment method provided by the above methods, the method comprising: based on the mathematical model of the grid-type photovoltaic grid-connected system, determining a complex torque model and a complex torque coefficient; wherein the mathematical model includes DC voltage additional control parameters; based on the complex torque model and the complex torque coefficient, estimating the system dominant oscillation frequency; according to the system dominant oscillation frequency and the complex torque coefficient, determining the stability criterion of the DC voltage additional control parameters in the grid-type photovoltaic grid-connected system; according to the stability criterion, adjusting the DC voltage additional control parameters.

[0073] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to execute the grid-connected photovoltaic DC voltage additional control parameter adjustment method provided by the above-mentioned methods, the method comprising: determining a complex torque model and a complex torque coefficient based on a mathematical model of the grid-connected photovoltaic grid-connected system; wherein the mathematical model includes DC voltage additional control parameters; estimating the system dominant oscillation frequency based on the complex torque model and the complex torque coefficient; determining the stability criterion of the DC voltage additional control parameters in the grid-connected photovoltaic grid-connected system according to the system dominant oscillation frequency and the complex torque coefficient; and adjusting the DC voltage additional control parameters according to the stability criterion.

[0074] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0075] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0076] Finally, 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for setting additional control parameters of grid-connected photovoltaic DC voltage, characterized in that: include: Based on the mathematical model of the grid-connected photovoltaic system, a complex torque model and a complex torque coefficient are determined; wherein the mathematical model includes a DC voltage additional control parameter; Based on the complex torque model and the complex torque coefficient, estimating the dominant oscillation frequency of the system; Determine the stability criterion of the additional control parameters of the DC voltage in the grid-connected photovoltaic system according to the dominant oscillation frequency and the complex torque coefficient of the system; According to the stability criterion, the DC voltage additional control parameter is adjusted.

2. The method for setting additional control parameters of grid-connected photovoltaic DC voltage according to claim 1, characterized in that: The mathematical model includes DC voltage and power angle; Accordingly, based on the mathematical model of the grid-connected photovoltaic system, the complex torque model and complex torque coefficient are determined, including: Based on the mathematical model, complex torque modeling is performed with the DC voltage and power angle as the dominant links of the grid-connected photovoltaic system to obtain the complex torque model; The mathematical model is simplified and derived to the complex torque model to obtain the complex torque coefficient.

3. The grid-connected photovoltaic DC voltage additional control parameter setting method according to claim 1 is characterized in that: The complex torque coefficient includes an equivalent damping torque coefficient and an equivalent synchronous torque coefficient; Accordingly, based on the complex torque model and the complex torque coefficient, the dominant oscillation frequency of the system is estimated, including: Based on the complex torque model, the dominant oscillation frequency of the system is estimated when the equivalent damping torque coefficient is approximately zero, so as to obtain an expression for the dominant oscillation frequency of the system; The equivalent synchronous torque coefficient is scaled, and the scaled equivalent synchronous torque coefficient is substituted into the expression of the dominant oscillation frequency of the system to obtain the estimated dominant oscillation frequency of the system.

4. The method for setting additional control parameters of grid-connected photovoltaic DC voltage according to claim 3 is characterized in that: According to the dominant oscillation frequency and complex torque coefficient of the system, the stability criterion of the additional control parameters of the DC voltage in the grid-connected photovoltaic grid-connected system is determined, including: Determine a conditional expression for the equivalent damping torque coefficient; Substituting the estimated system dominant oscillation frequency into the conditional expression, the stability criterion is obtained.

5. The method for setting additional control parameters of grid-connected photovoltaic DC voltage according to claim 4 is characterized in that: The conditional expression is as follows: ； The stability criterion is as follows: ； in, represents the equivalent damping torque coefficient, Indicates the DC voltage additional control integral coefficient, represents the damping coefficient of the virtual synchronous machine, represents the rated angular frequency, Indicates the DC voltage additional control proportional coefficient, represents the DC voltage dynamic equivalent coefficient, represents the synchronous power factor, Indicates the virtual synchronous inertia time constant.

6. The method for setting additional control parameters of grid-connected photovoltaic DC voltage according to claim 1, characterized in that: The mathematical model of the grid-connected photovoltaic system is defined as follows: ； The complex torque model is defined as follows: ； ； ； in, Indicates the inverter output active power, represents the damping coefficient of the virtual synchronous machine, represents the virtual synchronous angular frequency, represents the virtual synchronous inertia time constant, represents the Laplace operator, Indicates the DC voltage additional control proportional coefficient, Indicates the DC voltage additional control integral coefficient, represents the DC voltage, represents the composite angular frequency, represents the composite power angle, represents the rated angular frequency, Indicates the power base value, represents the DC capacitance, represents the synchronous power factor, represents the potential amplitude in the inverter, Indicates the grid voltage amplitude, Indicates the connection reactance between the inverter and the grid. represents the grid voltage phase angle, represents the equivalent damping torque coefficient, represents the equivalent synchronous torque coefficient, represents the dominant oscillation frequency of the system, Represents the dynamic equivalent coefficient of DC voltage.

7. A grid-type photovoltaic DC voltage additional control parameter setting device, characterized in that: include: A complex torque modeling module, used to determine a complex torque model and a complex torque coefficient based on a mathematical model of a grid-connected photovoltaic system; wherein the mathematical model includes a DC voltage additional control parameter; A system dominant oscillation frequency estimation module, used for estimating the system dominant oscillation frequency based on the complex torque model and the complex torque coefficient; A stability criterion determination module, used to determine a stability criterion for a DC voltage additional control parameter in a grid-connected photovoltaic grid-connected system according to the dominant oscillation frequency and complex torque coefficient of the system; The DC voltage additional control parameter setting module is used to set the DC voltage additional control parameter according to the stability criterion.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the method for setting additional control parameters of the grid-connected photovoltaic DC voltage according to any one of claims 1 to 6 is implemented.

9. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for setting additional control parameters of a grid-connected photovoltaic DC voltage is implemented as described in any one of claims 1 to 6.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the method for setting additional control parameters of a grid-connected photovoltaic DC voltage is implemented as described in any one of claims 1 to 6.

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