Transient synchronous stability control method of grid-type SVG based on AC / DC voltage hybrid control

Abstract

The present invention discloses a transient synchronous stability control method for a meshed SVG based on AC / DC voltage hybrid control, comprising: calculating the internal potential phase angle of the meshed SVG system based on operating parameter data of the meshed SVG system based on a DC voltage self-synchronous control module; judging whether the phase angle difference between the phase angle at a port of the meshed SVG system and the internal potential phase angle is less than 2°, and judging that the meshed SVG system is stable when the phase angle difference is less than or equal to 2°; implementing AC voltage stability enhancement control on the meshed SVG system when the phase angle difference exceeds 2°, and calculating the output current of the meshed SVG system; judging whether the output current reaches a preset current limit value; if the output current is greater than or equal to the current limit value, judging that the current of the meshed SVG system is saturated and there is a risk of instability, and implementing DC voltage stability enhancement control on the meshed SVG system.

Description

Technical Field

[0001] The present invention relates to the technical field of stability analysis of new energy power systems, and more specifically, to a transient synchronous stability control method for a grid-type SVG based on AC / DC voltage hybrid control. Background Art

[0002] With the rapid development of renewable energy, power systems are increasingly characterized by a high proportion of renewable energy and power electronic equipment. This change has led to a significant decrease in the grid's inertia and short-circuit capacity, weakening the system's stability and interference immunity, posing numerous challenges to the safe and stable operation of the power system. Previous studies have shown that static var generators (SVGs) can significantly improve system voltage stability when operating alongside grid-connected renewable energy systems. Existing SVGs often utilize a phase-locked loop (PLL) for grid synchronization and directly compensate renewable energy stations by controlling reactive current. However, the essence of reactive power compensation is to effectively support node voltages. Because SVGs are equivalent to variable admittance and current sources, and PLL control suffers from poor stability in weak grid conditions, they can typically only provide voltage support in a quasi-steady state. This limited voltage response speed makes it difficult to meet broadband voltage support requirements.

[0003] Research in recent years has shown that SVGs under grid-forming control offer significant advantages over PLL-based grid-following control in providing grid power and frequency support, particularly in their ability to operate independently in island mode. Furthermore, grid-forming control demonstrates greater robustness to grid strength. Its key feature is its departure from the traditional phase-locked loop-based frequency tracking mechanism, adopting grid-connected synchronization characteristics similar to those of traditional synchronous generators, resulting in voltage source characteristics. However, while emulating the inertia and damping characteristics of traditional synchronous generators, it inevitably inherits some of their inherent problems, such as transient stability and low-frequency oscillations. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention provides a transient synchronous stability control method for a grid-type SVG based on AC / DC voltage hybrid control.

[0005] According to one aspect of the present invention, a method for transient synchronous stability control of a grid-type SVG based on AC / DC voltage hybrid control is provided, comprising:

[0006] Construct a DC voltage self-synchronization control module for a grid-type SVG system;

[0007] Calculate the internal potential phase angle of the grid-type SVG system based on the operating parameter data of the grid-type SVG system based on the DC voltage self-synchronous control module;

[0008] Determine whether the phase angle difference between the port phase angle and the internal potential phase angle of the meshed SVG system is less than 2°, and if the phase angle difference is less than or equal to 2°, determine that the meshed SVG system is stable;

[0009] When the phase angle difference exceeds 2°, AC voltage stability enhancement control is implemented on the grid-type SVG system based on the DC voltage self-synchronization control module, and the output current of the grid-type SVG system is calculated;

[0010] Determine whether the output current of the meshed SVG system has reached the preset current limit value. If the output current is greater than or equal to the current limit value, the meshed SVG system is determined to be current saturated and there is a risk of instability. Then, DC voltage stability enhancement control is implemented on the meshed SVG system based on the DC voltage self-synchronization control module.

[0011] Optionally, the DC voltage self-synchronous control module is composed of DC synchronous control, reactive power droop control and AC voltage control, wherein the DC synchronous control is expressed as:

[0012] Where, Output phase for DC voltage synchronous control; is the DC voltage of SVG, It is the reference value for DC voltage control of SVG; T , J , D They are the proportional coefficient, inertia coefficient, and damping coefficient of DC voltage control; is the rated angular frequency; s is the Laplace operator;

[0013] Reactive power droop control is expressed as:

[0014] Where, V dref is the voltage d-axis component reference value, K Q is the reactive power droop coefficient, V 0 and Q 0 is the initial value of voltage and reactive power, where the reference value of voltage q-axis component in reactive power droop control is 0;

[0015] AC voltage control is:

[0016] in, is the d-axis component of the internal potential; is the q-axis component of the internal potential; 、 、 and is the transfer function expression of AC voltage control in the complex domain.

[0017] Optionally, the phase angle difference The calculation formula is:

[0018] in, is the internal potential phase angle; is the voltage phase angle at the port; is the d-axis component of the internal potential; is the q-axis component of the internal potential; The d-axis component of the voltage at the port; is the q-axis component of the voltage at the port.

[0019] Optionally, when the meshed SVG system is stable, the voltage q-axis control reference value of the meshed SVG system is set to 0 to operate the meshed SVG system.

[0020] Optionally, the AC voltage stability enhancement control is expressed as follows: let the voltage q-axis control reference value be:

[0021] Where, K V is the coefficient of AC voltage enhancement control; is the phase angle difference; is the d-axis component of the internal potential; is the q-axis component of the internal potential; The d-axis component of the voltage at the port; is the q-axis component of the voltage at the port.

[0022] Optionally, the output current I The calculation formula is:

[0023] in, I d is the d-axis component of the output current, I q is the q-axis component of the output current.

[0024] Optionally, determining whether the output current of the meshed SVG system reaches a preset current limit value further includes:

[0025] If the output current is less than the current limit value, the grid-type SVG system is determined to be stable.

[0026] Optionally, the DC synchronous control of the meshed SVG system when it is stable is:

[0027] in, The output phase of the DC voltage synchronization control is controlled by the internal potential , port voltage phase The relationship is , ; The d-axis component of the voltage at the port; is the q-axis component of the voltage at the port; the DC voltage stability enhancement control when the grid-type SVG system is current saturated and there is a risk of instability is:

[0028] Where, is the coefficient of DC voltage enhancement control; is the phase angle difference.

[0029] According to another aspect of the present invention, a grid-type SVG transient synchronous stability control device based on AC / DC voltage hybrid control is provided, comprising:

[0030] A construction module for constructing a DC voltage self-synchronization control module for a grid-type SVG system;

[0031] A calculation module, configured to calculate an internal potential phase angle of the meshed SVG system based on operating parameter data of the meshed SVG system based on the DC voltage self-synchronization control module;

[0032] a judgment module, configured to judge whether a phase angle difference between a phase angle at a port of the meshed SVG system and an internal potential phase angle is less than 2°, and to judge that the meshed SVG system is stable if the phase angle difference is less than or equal to 2°;

[0033] An AC voltage control module is used to implement AC voltage stability enhancement control for the meshed SVG system based on the DC voltage self-synchronization control module when the phase angle difference exceeds 2°, and calculate the output current of the meshed SVG system;

[0034] The DC voltage control module is used to determine whether the output current of the meshed SVG system has reached a preset current limit value. If the output current is greater than or equal to the current limit value, it is determined that the meshed SVG system is current saturated and there is a risk of instability. The DC voltage stability enhancement control of the meshed SVG system based on the DC voltage self-synchronization control module is implemented.

[0035] According to another aspect of the present invention, a computer-readable storage medium is provided, wherein the storage medium stores a computer program, and the computer program is used to execute the method according to any one of the above aspects of the present invention.

[0036] According to another aspect of the present invention, an electronic device is provided, comprising: a processor; a memory for storing instructions executable by the processor; and the processor for reading the executable instructions from the memory and executing the instructions to implement the method described in any one of the above aspects of the present invention.

[0037] Therefore, the present invention proposes a control strategy for AC / DC voltage mixing based on the principle of adaptive power angle compensation, which can effectively improve the transient stability performance of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0039] Figure 1 1 is a flow chart of a method for controlling transient synchronous stability of a grid-type SVG based on AC / DC voltage hybrid control according to an exemplary embodiment of the present invention;

[0040] Figure 2 This is another flow chart of a method for controlling transient synchronous stability of a grid-type SVG based on AC / DC voltage hybrid control provided by an exemplary embodiment of the present invention;

[0041] Figure 3 Schematic diagram of a new energy delivery system including a network-type SVG provided by an exemplary embodiment of the present invention;

[0042] Figure 4 This is a block diagram of a mesh-type SVG control provided by an exemplary embodiment of the present invention;

[0043] Figure 5 is a schematic diagram of an equivalent model of a new energy delivery system provided by an exemplary embodiment of the present invention;

[0044] Figure 6 Schematic diagram of a grid-following converter using LVRT provided by an exemplary embodiment of the present invention;

[0045] Figure 7a and Figure 7b They are respectively schematic diagrams of power angle characteristic curves of a combined transmission system before and after equivalence provided by an exemplary embodiment of the present invention;

[0046] Figure 8 1 is a schematic diagram of a power angle curve after considering the influence of DC capacitance according to an exemplary embodiment of the present invention;

[0047] Figure 9a 、 Figure 9b and Figure 9c Schematic diagrams of a power angle waveform of a joint transmission system, an active power response waveform of a grid-type SVG, and an active power response waveform of a new energy device, respectively, provided by an exemplary embodiment of the present invention;

[0048] Figure 10a 、 Figure 10b and Figure 10c They are respectively schematic diagrams of the power angle waveform of the joint transmission system after the improvement measures provided by an exemplary embodiment of the present invention, the active power response waveform of the grid-type SVG, and the active power response waveform of the new energy equipment;

[0049] Figure 11a and Figure 11b They are respectively schematic diagrams of power angle instability of a combined transmission system and waveforms of the combined transmission system after improvement measures are added, provided by an exemplary embodiment of the present invention;

[0050] Figure 12a and Figure 12b They are respectively schematic diagrams of simulation comparison of different control methods provided by an exemplary embodiment of the present invention;

[0051] Figure 13 1 is a schematic structural diagram of a grid-type SVG transient synchronous stability control device based on AC / DC voltage hybrid control provided by an exemplary embodiment of the present invention;

[0052] Figure 14 This is a structure of an electronic device provided by an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0053] Below, the exemplary embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments of the present invention, and it should be understood that the present invention is not limited to the exemplary embodiments described herein.

[0054] It should be noted that the relative arrangement of components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

[0055] Those skilled in the art will understand that the terms "first" and "second" in the embodiments of the present invention are only used to distinguish different steps, devices or modules, and neither represent any specific technical meaning nor indicate the necessary logical order between them.

[0056] It should also be understood that, in the embodiments of the present invention, “a plurality of” may refer to two or more than two, and “at least one” may refer to one, two or more than two.

[0057] It should also be understood that any component, data or structure mentioned in the embodiments of the present invention can generally be understood as one or more, unless explicitly limited or otherwise indicated in the context.

[0058] In addition, the term "and / or" in this invention merely describes an association relationship between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Furthermore, the character " / " in this invention generally indicates that the related objects are in an "or" relationship.

[0059] It should also be understood that the description of the various embodiments of the present invention focuses on the differences between the various embodiments, and the same or similar aspects thereof can be referenced with each other. For the sake of brevity, they will not be described one by one.

[0060] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0061] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0062] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0063] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0064] Embodiments of the present invention can be applied to electronic devices such as terminal devices, computer systems, and servers, and can operate in conjunction with numerous other general-purpose or specialized computing system environments or configurations. Examples of well-known terminal devices, computing systems, environments, and / or configurations suitable for use with terminal devices, computer systems, servers, and other electronic devices include, but are not limited to, personal computer systems, server computer systems, thin clients, thick clients, handheld or laptop devices, microprocessor-based systems, set-top boxes, programmable consumer electronics, network personal computers, minicomputer systems, mainframe computer systems, and distributed cloud computing technology environments including any of the above.

[0065] Electronic devices such as terminal devices, computer systems, and servers can be described in the general context of computer system-executable instructions (such as program modules) executed by a computer system. Generally, program modules can include routines, programs, object programs, components, logic, data structures, etc., which perform specific tasks or implement specific abstract data types. Computer systems / servers can be implemented in a distributed cloud computing environment, where tasks are performed by remote processing devices linked via a communication network. In a distributed cloud computing environment, program modules can be located on local or remote computing system storage media, including storage devices.

[0066] Exemplary Methods

[0067] Figure 1 This is a flow chart of a method for analyzing and improving transient synchronization stability of a networked SVG provided by an exemplary embodiment of the present invention. This embodiment can be applied to electronic devices, such as Figure 1 As shown, the network-type SVG transient synchronous stability analysis and improvement method 100 includes the following steps:

[0068] Step 101: construct a DC voltage self-synchronization control module of a grid-type SVG system;

[0069] Step 102, calculating the internal potential phase angle of the meshed SVG system based on the DC voltage self-synchronous control module;

[0070] Step 103: Determine whether the phase angle difference between the phase angle at the port and the internal potential phase angle of the meshed SVG system is less than 2°, and if the phase angle difference is less than or equal to 2°, determine that the meshed SVG system is stable.

[0071] Step 104 , when the phase angle difference exceeds 2°, performing AC voltage stability enhancement control on the meshed SVG system based on the DC voltage self-synchronization control module, and calculating the output current of the meshed SVG system;

[0072] Step 105 determines whether the output current of the meshed SVG system reaches a preset current limit value. If the output current is greater than or equal to the current limit value, it is determined that the meshed SVG system is current saturated and there is a risk of instability. DC voltage stability enhancement control is then implemented on the meshed SVG system based on the DC voltage self-synchronization control module.

[0073] Specifically, the present invention aims to theoretically analyze the interaction between the grid-type SVG and the new energy base, reveal the transient instability mechanism of the grid-type SVG, and propose a stability-enhanced self-synchronization control strategy based on the principle of adaptive power angle compensation, which can effectively improve the transient stability performance of the system. Figure 2As shown, the following steps are included:

[0074] 1) Construct a DC voltage self-synchronization control module for a grid-type SVG system;

[0075] 2) calculating an internal potential phase angle of the meshed SVG system based on operating parameter data of the meshed SVG system, and calculating a phase angle at a port of the meshed SVG system and a phase angle difference between the internal potential phase angles;

[0076] 3) determining whether a phase angle difference between a phase angle at a port of the meshed SVG system and the internal potential phase angle is less than a threshold value of 2°, and determining that the meshed SVG system is stable if the phase angle difference is less than 2°;

[0077] 4) Calculate the output current of the grid-type SVG system;

[0078] 5) Determine the output current of the meshed SVG system I Whether the limit value is reached I max , if the output current is greater than or equal to I max When the phase angle difference is greater than 2°, it is determined that the current of the grid-type SVG system is saturated and there is a risk of instability, and DC voltage stability enhancement control needs to be implemented on the grid-type SVG.

[0079] Furthermore, the step 1) DC voltage self-synchronous control consists of DC synchronous control, reactive power droop control, and AC voltage control, wherein the DC synchronous control is expressed as:

[0080] in, It is the output phase of DC voltage synchronous control, used for Park transformation to convert the voltage and current of the three phases abc into the dq coordinate system; is the DC voltage of SVG, It is the reference value for DC voltage control of SVG; T , J , D They are the proportional coefficient, inertia coefficient, and damping coefficient of DC voltage control; is the rated angular frequency, usually ; s is the Laplace operator.

[0081] Reactive power droop control is expressed as:

[0082] in, V dref is the voltage d-axis component reference value, K Q is the reactive power droop coefficient,V 0 and Q 0 is the initial value of voltage and reactive power.

[0083] The reference value of the voltage q-axis component is 0.

[0084] AC voltage control is:

[0085] in is the d-axis component of the internal potential, is the q-axis component of the internal potential; , , and is the transfer function expression of AC voltage control in the complex domain.

[0086] Furthermore, the phase angle difference in step 2) The calculation formula is:

[0087] in, is the internal potential phase angle; is the voltage phase angle at the port; is the d-axis component of the internal potential, is the q-axis component of the internal potential; The d-axis component of the voltage at the port, is the q-axis component of the voltage at the port.

[0088] Furthermore, in step 3) When the voltage q-axis control reference value is

[0089]

[0090] when When the voltage q-axis control reference value is

[0091] Where, K V is the coefficient of AC voltage enhancement control.

[0092] Furthermore, in step 4) outputting the current I The calculation formula is:

[0093] in, I d is the d-axis component of the output current, I q is the q-axis component of the output current.

[0094] like Then it is recorded as SVG current saturation, otherwise it is recorded as current unsaturation.

[0095] Furthermore, in step 5) if the current is not saturated or hour

[0096] in, The output phase of the DC voltage synchronous control is related to the internal potential and the port voltage phase. , ; is the DC voltage of SVG, It is the reference value for DC voltage control of SVG; T , J , D They are the proportional coefficient, inertia coefficient, and damping coefficient of DC voltage control; is the rated angular frequency, usually ; s is the Laplace operator.

[0097] When the current is saturated and When , in addition to adopting the AC voltage stability enhancement control method, it is also necessary to start the DC voltage stability enhancement control method and adjust the output of the DC voltage synchronous control, which is expressed as

[0098] in is the coefficient of DC voltage enhancement control.

[0099] Specific verification examples of the present invention:

[0100] In Matlab software, we create Figure 3 The simulation model shown in Figure 1 is shown in Figure 12. Among them, the power grid model adopts an ideal three-phase voltage source with a fixed voltage amplitude and frequency of 1p.u. and 50HZ, and the grid-type SVG adopts Figure 4 The control structure shown in the figure, the equivalent model of the new energy transmission system is as follows Figure 5 As shown, new energy stations use Figure 6 The grid-following converter shown is shown. X g 、 X s and X v is the corresponding branch reactance, E s and δ s is the amplitude and phase of the transient electromotive force of the network-type SVG, U v 、 U p and δ v 、 δ pThey are the amplitude and phase of the bus voltage at the new energy station and the collection point respectively. X F is the filter inductance of the device, C F The filter capacitor is controlled by a "power droop-voltage control loop-current control loop." The specific parameters used in the simulation are shown in Table 1.

[0101] Table 1 Parameter values of the system in the simulation verification of the embodiment

[0102]

[0103] Figure 7a and Figure 7b This is the power angle curve of the combined transmission system before and after equivalent verification by the embodiment of the present invention. Figure 7a and Figure 7b It can be seen that due to the active power injected by the new energy, the sinusoidal power angle curve P es Distortion occurs, which causes problems in the stability analysis of the system. Through equivalent modeling, the electromagnetic power of the combined transmission system can be always positive, which helps to understand and further analyze.

[0104] Figure 8 In order to consider the impact of DC capacitor dynamics on the transient synchronization stability of the system, the equivalent power angle curve of the system output is jointly sent. P E < P S From the dynamic equation of DC capacitor, we know that DC capacitor will absorb energy and cause DC voltage V DC Considering the voltage resistance of the capacitor, it is generally set V DC The maximum voltage that can be achieved is 1.1 to 1.15 times the rated voltage. When the voltage on both sides of the capacitor exceeds this value, the energy-consuming element starts to consume the excess energy and maintain the constant DC voltage, thereby achieving the purpose of protecting the equipment. DC Increase to the critical value, that is P eqe_c In the most severe drop situation, the DC capacitor has the most serious impact on system stability. The acceleration area of the equivalent system changes from A1 to A1+A2, and the deceleration area changes from D1+D2 to D1. The system is more likely to cross the stable equilibrium point.

[0105] Figure 9a to Figure 9cTo verify the waveform diagram of the power angle stability characteristics of the combined transmission system, it can be seen from the figure that when the active power provided by the renewable energy source before the fault occurs is large, the combined transmission system has the risk of power angle instability. In addition, the active power obtained by the grid-type SVG during the fault period becomes negative, and its absolute value is basically the same as the active power output of the renewable energy source.

[0106] Figure 10a to Figure 10c After adopting the improvement measures, the system is in different K θ The power angle curve and the waveform of each system variable under the control strategy can be seen. P meqf , which reduces the acceleration area of the system in disguise, and improves the transient stability performance of the system.

[0107] also, Figure 11a and Figure 11b The hardware simulation based on RT-LAB can also illustrate the correctness of the mechanism analysis and the effectiveness of the improvement measures.

[0108] In order to further verify the superiority of the improvement measures proposed in this paper, Figure 12a For U: 1.0pu→0.5pu, Figure 12b Figure 2 is a schematic diagram of simulation results under different control modes of U: 1.0pu→0p.u. Table 2 shows the waveforms and critical removal times corresponding to different improvement measures under different voltage drop levels.

[0109] Table 2 Limit clearing time under different fault conditions

[0110]

[0111] Therefore, this invention proposes a hybrid AC / DC voltage control strategy based on the principle of adaptive power angle compensation, which effectively improves the system's transient stability. This strategy can mitigate transient instability caused by power imbalance in grid-connected SVGs during transient conditions, improving the system's transient stability margin. Compared with other improvement measures, the proposed control strategy can ensure the grid's transient stability under more severe fault conditions.

[0112] Exemplary devices

[0113] Figure 13 FIG. 1 is a schematic diagram of a structure of a network-type SVG transient synchronous stability analysis and improvement device provided by an exemplary embodiment of the present invention. Figure 13 As shown, the apparatus 1300 includes:

[0114] A construction module 1310 is used to construct a DC voltage self-synchronization control module of a grid-type SVG system;

[0115] A calculation module 1320 is configured to calculate an internal potential phase angle of the meshed SVG system based on the operating parameter data of the meshed SVG system based on the DC voltage self-synchronization control module;

[0116] A determination module 1330 is configured to determine whether a phase angle difference between a phase angle at a port of the meshed SVG system and an internal potential phase angle is less than 2°, and to determine that the meshed SVG system is stable if the phase angle difference is less than or equal to 2°.

[0117] AC voltage control module 1340, configured to implement AC voltage stability enhancement control on the meshed SVG system based on the DC voltage self-synchronization control module when the phase angle difference exceeds 2°, and calculate the output current of the meshed SVG system;

[0118] The DC voltage control module 1350 is used to determine whether the output current of the meshed SVG system has reached a preset current limit value. If the output current is greater than or equal to the current limit value, the meshed SVG system is determined to be current saturated and there is a risk of instability. The meshed SVG system, based on the DC voltage self-synchronization control module, is then subject to DC voltage stability enhancement control.

[0119] Optionally, the DC voltage self-synchronous control module is composed of DC synchronous control, reactive power droop control and AC voltage control, wherein the DC synchronous control is expressed as:

[0120] Where, Output phase for DC voltage synchronous control; is the DC voltage of SVG, It is the reference value for DC voltage control of SVG; T , J , D They are the proportional coefficient, inertia coefficient, and damping coefficient of DC voltage control; is the rated angular frequency; s is the Laplace operator;

[0121] Reactive power droop control is expressed as:

[0122] Where, V dref is the voltage d-axis component reference value, K Q is the reactive power droop coefficient, V 0 and Q 0 is the initial value of voltage and reactive power, where the reference value of voltage q-axis component in reactive power droop control is 0;

[0123] AC voltage control is:

[0124] in, is the d-axis component of the internal potential; is the q-axis component of the internal potential; 、 、 and is the transfer function expression of AC voltage control in the complex domain.

[0125] Optionally, the phase angle difference The calculation formula is:

[0126] in, is the internal potential phase angle; is the voltage phase angle at the port; is the d-axis component of the internal potential; is the q-axis component of the internal potential; The d-axis component of the voltage at the port; is the q-axis component of the voltage at the port.

[0127] Optionally, when the meshed SVG system is stable, the voltage q-axis control reference value of the meshed SVG system is set to 0 to operate the meshed SVG system.

[0128] Optionally, the AC voltage stability enhancement control is expressed as follows: let the voltage q-axis control reference value be:

[0129] Where, K V is the coefficient of AC voltage enhancement control; is the phase angle difference; is the d-axis component of the internal potential; is the q-axis component of the internal potential; The d-axis component of the voltage at the port; is the q-axis component of the voltage at the port.

[0130] Optionally, the output current I The calculation formula is:

[0131] in, I d is the d-axis component of the output current, I q is the q-axis component of the output current.

[0132] Optionally, determining whether the output current of the meshed SVG system reaches a preset current limit value further includes:

[0133] If the output current is less than the current limit value, the grid-type SVG system is determined to be stable.

[0134] Optionally, the DC synchronous control of the meshed SVG system when it is stable is:

[0135] in, The output phase of the DC voltage synchronization control is controlled by the internal potential , port voltage phase The relationship is , ; The d-axis component of the voltage at the port; is the q-axis component of the voltage at the port;

[0136] The DC voltage stability enhancement control when the grid-type SVG system is current saturated and has the risk of instability is as follows:

[0137] Where, is the coefficient of DC voltage enhancement control; is the phase angle difference.

[0138] Exemplary electronic devices

[0139] Figure 14 This is the structure of an electronic device provided by an exemplary embodiment of the present invention. Figure 14 As shown, the electronic device 140 includes one or more processors 141 and a memory 142 .

[0140] The processor 141 may be a central processing unit (CPU) or other forms of processing units having data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions.

[0141] Memory 142 may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. Volatile memory may include, for example, random access memory (RAM) and / or cache memory. Non-volatile memory may include, for example, read-only memory (ROM), a hard disk, flash memory, etc. One or more computer program instructions may be stored on the computer-readable storage medium, and the processor 141 may execute the program instructions to implement the software program methods and / or other desired functions of the various embodiments of the present invention described above. In one example, the electronic device may further include an input device 143 and an output device 144, which are interconnected via a bus system and / or other form of connection mechanism (not shown).

[0142] In addition, the input device 143 may also include, for example, a keyboard, a mouse, and the like.

[0143] The output device 144 can output various information to the outside. The output device 144 can include, for example, a display, a speaker, a printer, a communication network and a remote output device connected thereto.

[0144] Of course, to simplify, Figure 14 Only some of the components related to the present invention in the electronic device are shown, and components such as a bus, an input / output interface, etc. are omitted. In addition, the electronic device may further include any other appropriate components according to specific application conditions.

[0145] Exemplary computer program products and computer-readable storage media

[0146] In addition to the above-mentioned methods and devices, an embodiment of the present invention may also be a computer program product, which includes computer program instructions, which, when executed by a processor, enable the processor to perform the steps of the method according to various embodiments of the present invention described in the above "Exemplary Method" section of this specification.

[0147] The computer program product may be written in any combination of one or more programming languages to implement the operations of embodiments of the present invention, including object-oriented programming languages such as Java, C++, and conventional procedural programming languages such as C or similar programming languages. The program code may be executed entirely on the user's computing device, partially on the user's computing device, as a stand-alone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0148] In addition, an embodiment of the present invention may also be a computer-readable storage medium having computer program instructions stored thereon, which, when executed by a processor, enable the processor to execute the steps of the method according to various embodiments of the present invention described in the above "Exemplary Method" section of this specification.

[0149] The computer-readable storage medium may be any combination of one or more readable media. The readable medium may be a readable signal medium or a readable storage medium. The readable storage medium may include, for example, but is not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, system, or device, or any combination thereof. More specific examples (a non-exhaustive list) of readable storage media include: an electrical connection having one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof.

[0150] The basic principles of the present invention have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, and effects mentioned in the present invention are merely illustrative and non-limiting, and should not be construed as necessarily possessed by each embodiment of the present invention. Furthermore, the specific details disclosed above are provided for illustrative purposes and to facilitate understanding, and are not intended to be limiting. These details do not necessarily limit the present invention to being implemented using these specific details.

[0151] Each embodiment in this specification is described in a progressive manner, with each embodiment focusing on its differences from the other embodiments. References to the same or similar parts between the various embodiments are sufficient. For system embodiments, since they largely correspond to method embodiments, their description is relatively simple. For relevant parts, references to the description of the method embodiments are sufficient.

[0152] The block diagrams of the devices, systems, equipment, and systems involved in the present invention are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As will be appreciated by those skilled in the art, these devices, systems, equipment, and systems can be connected, arranged, or configured in any manner. Words such as "including," "comprising," "having," and the like are open-ended words, meaning "including but not limited to," and can be used interchangeably therewith. The words "or" and "and" used herein refer to the words "and / or" and can be used interchangeably therewith, unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to," and can be used interchangeably therewith.

[0153] The method and system of the present invention may be implemented in many ways. For example, the method and system of the present invention may be implemented by software, hardware, firmware, or any combination of software, hardware, and firmware. The above sequence of steps for the method is for illustration only, and the steps of the method of the present invention are not limited to the sequence specifically described above, unless otherwise specified. In addition, in some embodiments, the present invention may also be implemented as a program recorded in a recording medium, which includes machine-readable instructions for implementing the method according to the present invention. Thus, the present invention also covers recording media that store programs for executing the method according to the present invention.

[0154] It should also be noted that, in the system, device and method of the present invention, each component or each step can be decomposed and / or recombined. These decompositions and / or recombinations should be regarded as equivalent schemes of the present invention. The above description of the disclosed aspects is provided to enable any technician in this field to make or use the present invention. Various modifications to these aspects will be very obvious to those skilled in the art, and the general principles defined here can be applied to other aspects without departing from the scope of the present invention. Therefore, the present invention is not intended to be limited to the aspects shown here, but according to the widest scope consistent with the principles disclosed here and novel features.

[0155] The above description has been provided for the purpose of illustration and description. Furthermore, this description is not intended to limit the embodiments of the present invention to the forms disclosed herein. Although a number of example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A method for transient synchronous stability control of a grid-type SVG based on AC / DC voltage hybrid control, characterized in that: include: Constructing a DC voltage self-synchronization control module for a grid-type SVG system, wherein the DC voltage self-synchronization control module comprises DC synchronization control, reactive power droop control, and AC voltage control; Calculating an internal potential phase angle of the meshed SVG system based on the operating parameter data of the meshed SVG system based on the DC voltage self-synchronization control module; Determining whether a phase angle difference between a phase angle at a port of the meshed SVG system and the internal potential phase angle is less than 2°, and determining that the meshed SVG system is stable if the phase angle difference is less than or equal to 2°; When the phase angle difference exceeds 2°, performing AC voltage stability enhancement control on the meshed SVG system based on the DC voltage self-synchronization control module, and calculating the output current of the meshed SVG system; Determine whether the output current of the meshed SVG system reaches a preset current limit value; if the output current is greater than or equal to the current limit value, determine that the meshed SVG system is current saturated and there is a risk of instability, and implement DC voltage stability enhancement control on the meshed SVG system based on the DC voltage self-synchronization control module.

2. The method according to claim 1, characterized in that The DC synchronous control is expressed as: Where, Output phase for DC voltage synchronous control; is the DC voltage of SVG, It is the reference value for DC voltage control of SVG; T , J , D They are the proportional coefficient, inertia coefficient, and damping coefficient of DC voltage control; is the rated angular frequency; s is the Laplace operator; The reactive power droop control is expressed as: Where, V dref is the voltage d-axis component reference value, K Q is the reactive power droop coefficient, V 0 and Q 0 is the given initial value of voltage and reactive power, wherein the reference value of the voltage q-axis component in the reactive power droop control is 0; The AC voltage control is: in, is the d-axis component of the internal potential; is the q-axis component of the internal potential; 、 、 and is the transfer function expression of AC voltage control in the complex domain.

3. The method according to claim 1, characterized in that The phase angle difference The calculation formula is: in, is the internal potential phase angle; is the voltage phase angle at the port; is the d-axis component of the internal potential; is the q-axis component of the internal potential; The d-axis component of the voltage at the port; is the q-axis component of the voltage at the port.

4. The method according to claim 1, wherein When the meshed SVG system is stable, the voltage q-axis control reference value of the meshed SVG system is set to 0 to operate the meshed SVG system.

5. The method according to claim 1, wherein The AC voltage stability enhancement control is expressed as follows: let the voltage q-axis control reference value be: Where, K V is the coefficient of AC voltage enhancement control; is the phase angle difference; is the d-axis component of the internal potential; is the q-axis component of the internal potential; The d-axis component of the voltage at the port; is the q-axis component of the voltage at the port.

6. The method according to claim 1, characterized in that Output current I The calculation formula is: in, I d is the d-axis component of the output current, I q is the q-axis component of the output current.

7. The method according to claim 1, characterized in that Determining whether the output current of the meshed SVG system reaches a preset current limit value further includes: If the output current is less than the current limit value, it is determined that the meshed SVG system is stable.

8. The method according to claim 2, characterized in that The DC synchronous control of the grid-type SVG system when it is stable is: in, The output phase of the DC voltage synchronization control is controlled by the internal potential , port voltage phase The relationship is , ; The d-axis component of the voltage at the port; is the q-axis component of the voltage at the port; The DC voltage stability enhancement control when the grid-type SVG system is current saturated and has the risk of instability is as follows: Where, is the coefficient of DC voltage enhancement control; is the phase angle difference.

9. A grid-type SVG transient synchronous stability control device based on AC / DC voltage hybrid control, characterized in that: include: A construction module for constructing a DC voltage self-synchronization control module of a grid-type SVG system, wherein the DC voltage self-synchronization control module is composed of DC synchronization control, reactive power droop control, and AC voltage control; a calculation module, configured to calculate an internal potential phase angle of the meshed SVG system based on the operating parameter data of the meshed SVG system based on the DC voltage self-synchronization control module; a judgment module, configured to judge whether a phase angle difference between a phase angle at a port of the meshed SVG system and the internal potential phase angle is less than 2°, and to judge that the meshed SVG system is stable if the phase angle difference is less than or equal to 2°; an AC voltage control module, configured to implement AC voltage stability enhancement control on the meshed SVG system based on the DC voltage self-synchronization control module when the phase angle difference exceeds 2°, and calculate the output current of the meshed SVG system; A DC voltage control module is configured to determine whether the output current of the meshed SVG system has reached a preset current limit value. If the output current is greater than or equal to the current limit value, the meshed SVG system is determined to be current saturated and at risk of instability, and DC voltage stability enhancement control is implemented on the meshed SVG system based on the DC voltage self-synchronization control module.

10. A computer-readable storage medium, characterized in that The storage medium stores a computer program, and the computer program is used to execute the method according to any one of claims 1 to 8.

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