A method, system and device for flux inertia control of grid-forming converters based on synchronous condenser characteristics

Abstract

The application discloses a network-constructed converter magnetic flux inertia control method, system and equipment based on synchronous phase modifier characteristics, and relates to the technical field of power system control. The application aims to solve the problem of insufficient voltage support capability caused by inertia reduction in a high-proportion new energy power system. The application comprises establishing a dynamic model of a synchronous phase modifier; based on the dynamic model, a transfer function relationship is derived, with the change amount of grid voltage amplitude as input and the change amount of phase modifier d-axis current as output; then, based on the transfer function relationship, the real part of a complex number is taken at a preset frequency point, and the proportional, integral and differential parameters required for magnetic flux inertia support control are calculated; the voltage outer loop of the network-constructed converter is transformed into a PID control structure, and the magnetic flux inertia support control is realized. The application can effectively improve the voltage support capability and dynamic response performance of the network-constructed converter, and enhance the stability of the new power system.

Description

Technical Field

[0001] This invention relates to the field of power system control technology, and in particular to a method, system and equipment for controlling the magnetic flux inertia of a grid-type converter based on the characteristics of a synchronous condenser. Background Technology

[0002] With the rapid development and large-scale grid connection of new energy power generation technologies, my country's power system is gradually forming a new "dual-high" power system characterized by a high proportion of new energy and a high proportion of power electronic equipment. Grid-Forming Converters (GFMs), as key equipment supporting the stable operation of the power grid, have a significant impact on system voltage stability, frequency response, and small-disturbance stability due to their control strategies. Especially in scenarios with high penetration rates of new energy, system inertia decreases, voltage support capacity is insufficient, and problems such as wide-frequency oscillations and voltage instability are prone to occur, seriously affecting power grid security.

[0003] Currently, control methods for grid-type converters mainly include voltage source control (VSC) and virtual synchronous generator (VSG), aiming to enhance the system's inertia and damping by simulating the external characteristics of synchronous generators. However, existing control strategies often fail to fully integrate the dynamic response characteristics of synchronous condensers, especially in the coordinated control of the excitation system and the converter, resulting in room for improvement in the system's voltage recovery capability and dynamic response performance under disturbances. Traditional methods mostly rely on time-domain simulation, eigenvalue analysis, or impedance model analysis. These methods are either computationally complex, require high model accuracy, or are difficult to directly guide controller parameter design, lacking a parameter tuning method that has both clear physical meaning and is easy to implement in engineering.

[0004] Therefore, it is necessary to study the coupling mechanism between synchronous condensers and grid-type converters based on their dynamic characteristics, and propose a magnetic flux inertia control method based on the external characteristics of synchronous condensers to improve the voltage support capability and dynamic response performance of converters and enhance the stability of high-proportion new energy power systems. Summary of the Invention

[0005] The technical problem to be solved and the technical task proposed by this invention is to improve and refine existing technical solutions, and to provide a method, system, and device for controlling the magnetic flux inertia of a grid-type converter based on the characteristics of a synchronous condenser, so as to improve the voltage support capability and dynamic response performance of the converter and enhance the stability of a high-proportion renewable energy power system. To this end, this invention adopts the following technical solution.

[0006] The first technical solution of the present invention is: a method for controlling the magnetic flux inertia of a grid-type converter based on the characteristics of a synchronous condenser, comprising the following steps:

[0007] 1) Establish a dynamic model of the synchronous condenser. The dynamic model includes a first equation consisting of the relationship between the terminal voltage, the q-axis subtransient electromotive force and the d-axis current, a second equation consisting of the dynamic process of the q-axis transient electromotive force, a third equation consisting of the dynamic process of the q-axis subtransient electromotive force, and an excitation system transfer function consisting of the input-output relationship of the excitation system.

[0008] 2) Based on the dynamic model, the transfer function relationship with the change in grid voltage amplitude as input and the change in d-axis current of the synchronous condenser as output is derived;

[0009] 3) Based on the transfer function relationship, at a preset frequency point, by taking the real part of the complex number, the proportional, integral, and differential parameters required for magnetic flux inertia support control are calculated;

[0010] 4) Modify the voltage outer loop of the grid converter into a proportional, integral, and derivative control structure, and input the calculated proportional, integral, and derivative parameters to realize the magnetic flux inertia support control of the grid converter.

[0011] This technical solution starts with the electromagnetic dynamic equations of synchronous condensers, a traditional pillar of power grid stability. By establishing and utilizing a detailed dynamic model of the synchronous condenser, including its windings and excitation system, the subsequently derived control law can realistically simulate the electromagnetic response of a synchronous motor under grid voltage disturbances, enhancing the dynamic compatibility and coordination between the grid-connected converter and the traditional power system based on synchronous condensers. This solution derives the transfer function relationship from grid voltage to reactive current and calculates PID parameters based on this function, providing a clear physical meaning and mathematical basis for parameter tuning. This ensures that parameter values ​​are based on sound criteria, greatly improving the scientific rigor and reliability of the design. By injecting the PID parameters designed based on the dynamic characteristics of synchronous condensers into the voltage outer loop of the grid-connected converter, it can reproduce the inertial characteristics of flux establishment and decay similar to those of synchronous condensers when responding to grid voltage fluctuations. This suppresses abrupt voltage changes, smooths the voltage dynamic process, and effectively improves the voltage support strength and stability of the converter in grids with high penetration rates of new energy sources.

[0012] As a preferred technical means: the excitation system transfer function in step 1) has a numerator containing the product of the steady-state gain of the excitation system and two first-order leading elements, and a denominator containing the product of a first-order lagging element and two first-order inertial elements; the output voltage of the excitation system is obtained by passing the difference between the terminal voltage and the reference voltage through the transfer function and taking the negative sign.

[0013] The numerator of the excitation system transfer function in this technical solution uses the product of steady-state gain and two first-order leading elements, effectively improving the system's rapid response capability in the early stages of disturbances and helping to suppress voltage fluctuations in a timely manner. The denominator uses the product of a first-order lag element and two first-order inertial elements, which together ensure the smoothness and stability of the control output, avoiding overshoot and oscillation. Finally, by passing the difference between the generator terminal voltage and the reference voltage through this transfer function and taking the negative sign as the output, a voltage negative feedback control loop with clear dynamic characteristics is constructed, thereby significantly enhancing the overall support strength and dynamic regulation quality of the excitation system for the grid voltage.

[0014] As a preferred technical means: the transfer function in step 2) is F(s)+K; where F(s) is the s-domain transfer function derived based on the synchronous condenser dynamic model, and K is a constant calculated based on the d-axis subtransient reactance and transformer reactance.

[0015] This technical solution achieves the decomposition and reconstruction of the electromagnetic response of a synchronous condenser: F(s) derived from the dynamic model reflects the dynamic process and frequency dependence characteristics brought about by the system's excitation winding, time constant, etc., while the constant K, directly determined by the reactance parameter, represents the system's instantaneous reactive response capability; it not only clearly separates the dynamic and static components of the control, but also enables the controller design to simultaneously take into account fast initial response and accurate steady-state performance, providing a reliable theoretical basis for the accurate calculation of subsequent controller parameters.

[0016] As a preferred technical means: the transfer function relationship in step 2) is composed of a fractional term and a constant term; wherein, the numerator of the fractional term includes a differential term related to the difference between the d-axis transient and subtransient reactances and the transient time constant, and an algebraic term related to the d-axis synchronous reactance, subtransient reactance and the excitation system transfer function; its denominator includes a second-order term related to multiple reactance parameters and time constants, and a term related to the d-axis synchronous reactance, transformer reactance and the excitation system transfer function, and the fraction as a whole is divided by the sum of the d-axis subtransient reactance and the transformer reactance; the constant term is the negative reciprocal of the sum of the d-axis subtransient reactance and the transformer reactance.

[0017] This technical solution separates and characterizes two different physical response mechanisms of synchronous condensers under grid voltage disturbances by explicitly decomposing the transfer function into a mathematical structure consisting of a complex fractional term and a simple constant term. The constant term directly corresponds to the instantaneous reactive current increment determined by the subtransient reactance and transformer leakage reactance, ensuring the control system's rapid initial response capability to voltage surges. The fractional term, on the other hand, fully describes the complex high-frequency dynamic process and oscillation characteristics generated by the excitation system dynamics, winding transient processes, and their interactions. This allows the final controller design to simultaneously consider both the speed of response and the smooth stability of the dynamic process, laying a solid model foundation for accurately reproducing the complete external characteristics of the synchronous condenser.

[0018] As a preferred technical means: the proportional parameter in step 3) is calculated as follows: the sum of the fractional term and a constant term is taken as the complex real part at the first preset frequency; the integral parameter is calculated as follows: the sum of the fractional term and the constant term is multiplied by the complex frequency variable, and the complex real part is taken at the second preset frequency; the differential parameter is calculated as follows: the sum of the fractional term and the constant term is divided by the complex frequency variable, and the complex real part is taken at the third preset frequency; wherein, the constant term is the negative reciprocal of the sum of the d-axis subtransient reactance and the transformer reactance.

[0019] By performing rigorous frequency domain operations on the combined transfer function at specific frequency points and extracting the real part to calculate PID parameters, the designed proportional, integral, and derivative controllers can match the dynamic response characteristics of the synchronous condenser at key frequencies. This transforms the abstract mathematical model into controller parameters with clear physical meaning and excellent control performance, effectively ensuring that the grid-type converter can provide accurate damping and inertia support in different oscillation modes.

[0020] As a preferred technical means: the voltage outer loop control structure of the grid converter in step 4) has an output consisting of the sum of a proportional term, an integral term and a derivative term, wherein the proportional term is the proportional parameter, the integral term is the integral parameter divided by the complex frequency variable, and the derivative term is the derivative parameter multiplied by the complex frequency variable.

[0021] By directly configuring the calculated proportional, integral, and derivative parameters into the standard PID control structure, direct and accurate execution in the grid-type converter is achieved, ensuring that the dynamic response characteristics expected by theoretical calculation can be transformed into actual control effects. This allows for a simple and efficient engineering replication of the magnetic flux inertia support function of the synchronous condenser.

[0022] The second technical solution of the present invention is: a magnetic flux inertia control system for a grid-type converter based on the characteristics of a synchronous condenser, comprising:

[0023] The model building module is used to establish a dynamic model of the synchronous condenser. The dynamic model includes a first equation consisting of the relationship between the terminal voltage, the q-axis subtransient electromotive force and the d-axis current, a second equation consisting of the dynamic process of the q-axis transient electromotive force, a third equation consisting of the dynamic process of the q-axis subtransient electromotive force, and an excitation system transfer function consisting of the input-output relationship of the excitation system.

[0024] The function derivation module is used to derive the transfer function relationship based on the dynamic model, with the change in grid voltage amplitude as input and the change in d-axis current of the synchronous condenser as output.

[0025] The parameter calculation module is used to calculate the proportional, integral, and differential parameters required for magnetic flux inertia support control at a preset frequency point by taking the complex real part based on the transfer function relationship.

[0026] The controller configuration and execution module is used to transform the voltage outer loop of the grid-type converter into a proportional, integral, and derivative control structure, and input the calculated proportional, integral, and derivative parameters to realize the magnetic flux inertia support control of the grid-type converter.

[0027] This technical solution, through its function derivation and parameter calculation modules, ensures that the theoretical control law derived from the physical model of the synchronous condenser can be completely and accurately transformed into specific, executable controller parameters. This effectively prevents distortion or deviations that may occur during manual transmission and implementation. Since the control parameters are calculated through mathematical models and frequency domain analysis, rather than through trial and error tuning, the dynamic performance of the grid-connected converter configured by this system is predictable and repeatable, providing a guarantee for the planning and stable operation of the power grid. This system integrates a complete technical solution encompassing modeling, analysis, calculation, and execution functions. It clearly defines all links from data input to control implementation, forming a closed loop, and possesses practicality and operability.

[0028] As a preferred technical means: the excitation system transfer function defined in the model construction module has a numerator containing the product of the excitation system steady-state gain and two first-order leading elements, and a denominator containing the product of a first-order lag element and two first-order inertial elements; the output voltage of the excitation system is obtained by passing the difference between the terminal voltage and the reference voltage through the transfer function and taking the negative sign.

[0029] The transfer function relationship is composed of a fractional term and a constant term. The numerator of the fractional term includes a differential term related to the difference between the d-axis transient and subtransient reactances and the transient time constant, and an algebraic term related to the d-axis synchronous reactance, subtransient reactance, and excitation system transfer function. The denominator includes a second-order term related to multiple reactance parameters and time constants, and a term related to the d-axis synchronous reactance, transformer reactance, and excitation system transfer function. The fraction as a whole is divided by the sum of the d-axis subtransient reactance and the transformer reactance. The constant term is the negative reciprocal of the sum of the d-axis subtransient reactance and the transformer reactance.

[0030] The model in this technical solution not only includes the synchronous reactance that determines steady-state performance, but also incorporates parameters that determine transient and subtransient processes. This allows the derived transfer function to simultaneously describe the reactive current output changes of the synchronous machine at the initial instant (subtransient), intermediate (transient), and final (steady-state) stages after a disturbance, thus completely simulating its true electromagnetic inertia (i.e., magnetic flux inertia). Embedding the excitation system transfer function as a key variable into the main transfer function not only reflects the electromagnetic characteristics of the synchronous condenser itself but also embodies the dynamic response of its automatic voltage regulation system. This is something that many traditional virtual synchronous machine methods neglect, yet it is crucial for the system voltage recovery speed and stability. The constant term represents the instantaneous, zero-delay reactive current increment that the converter can provide at the initial instant of a disturbance, due to the path formed by the d-axis subtransient reactance and the transformer leakage reactance, ensuring that the control system has the ability to quickly support the initial voltage. The fractional terms describe the complex changes in magnetic flux and induced electromotive force in the windings of the synchronous condenser under the action of the excitation system. The differential term in the numerator determines the response speed, while the algebraic term determines the steady-state offset. The second-order structure of the denominator characterizes the system's inherent oscillation mode, determining the smoothness, stability, and potential for overshoot or oscillation during voltage recovery. This structural decoupling allows for a clear understanding and separate optimization of the system's immediate resistance to disturbances and dynamic recovery quality during subsequent controller design.

[0031] As a preferred technical means, the parameter calculation module is configured as follows:

[0032] The proportional parameter is calculated as follows: the sum of the fractional term and the constant term is taken as the complex real part at the first preset frequency;

[0033] The integral parameter is calculated as follows: the sum of the fractional term and the constant term is multiplied by the complex frequency variable, and the real part of the complex number is taken at the second preset frequency;

[0034] The differential parameter is calculated as follows: the sum of the fractional term and the constant term is divided by the complex frequency variable, and the real part of the complex number is taken at the third preset frequency.

[0035] The constant term is the negative reciprocal of the sum of the d-axis subtransient reactance and the transformer reactance;

[0036] In the controller configuration and execution module, the voltage outer loop control structure of the grid-type converter has an output consisting of the sum of a proportional term, an integral term, and a derivative term. The proportional term is the proportional parameter, the integral term is the integral parameter divided by the complex frequency variable, and the derivative term is the derivative parameter multiplied by the complex frequency variable.

[0037] This technical solution uses a mathematical mapping method based on the extraction of the real part in the frequency domain to transform the combined transfer function characterizing the dynamic characteristics of the synchronous condenser into the proportional, integral, and derivative parameters of the PID controller. It then uses a standard PID control structure to implement this, thereby theoretically ensuring the matching between the controller parameters and the target physical characteristics. In engineering, it achieves the high-fidelity and distortion-free injection of the "magnetic flux inertia" characteristics described by the complex model into the actual voltage control outer loop of the grid-type converter.

[0038] The third technical solution of the present invention is: a computer device, the device including one or more processors and one or more memories, wherein the one or more memories store at least one piece of program code, and when the program code is executed by the one or more processors, it implements the aforementioned method for controlling the magnetic flux inertia of a grid-type converter based on the characteristics of a synchronous condenser.

[0039] Beneficial effects: It solves the key challenge of how to accurately simulate and replace the external characteristics of synchronous generators using grid-type converters in "high-voltage and high-efficiency" power systems. Specifically, it is reflected in:

[0040] 1. This technical solution starts with the "electromagnetic transient equation" of the synchronous condenser, focuses on its "excitation system" and "winding dynamics", and aims to simulate its "magnetic flux inertia". It grasps the essence of the synchronous machine supporting voltage and providing reactive power, and realizes the deepening from "mechanical simulation" to "electromagnetic simulation".

[0041] The parameters, equations, and derived transfer functions in this technical solution correspond one-to-one with the specific electromagnetic processes and physical structures inside the synchronous condenser, making the entire control strategy a "white box" model with clear physical meaning, thus enhancing the credibility and interpretability of the technology.

[0042] 2. This technical solution directly analyzes and calculates controller parameters from the mathematical model. By establishing an accurate model → deriving the transfer function → calculating parameters in the frequency domain, the parameter design is objective, without relying on the engineer's experience, and without spending a lot of time-domain simulation or tedious trial and error to tune it. It is efficient and easy to find the optimal solution.

[0043] By decomposing the transfer function into dynamic and static parts and calculating the PID parameters by taking the real part at different frequency points, the instantaneous response capability and transient process dynamics of the system are captured. This ensures that the controller can respond quickly to disturbances and guarantee the smoothness and stability of the dynamic process, avoiding overshoot and oscillation.

[0044] 3. By replicating the flux establishment and decay process of a synchronous condenser, the grid-type converter is endowed with voltage inertia characteristics. When the grid voltage changes abruptly, the converter will not immediately and abruptly change its reactive power output, but will exhibit a smooth transition process with inertia, effectively suppressing voltage fluctuations, damping system oscillations, and significantly improving the voltage stability of the grid.

[0045] This technical solution is based on a control strategy that utilizes the external characteristics of a synchronous machine. Its output impedance characteristics are closer to those of a traditional synchronous power supply, which allows it to better integrate with the grid impedance, reduce the risk of subsynchronous or high-frequency oscillations, and improve the system's stability under small disturbances.

[0046] 4. This technical solution enables grid-connected converters to closely approximate or even be equivalent to synchronous condensers in terms of external characteristics, providing a direct and reliable technical path for grid-connected energy storage power stations to replace existing synchronous condensers. Simultaneously, it facilitates coordinated control with existing synchronous condensers to jointly maintain grid stability.

[0047] Since the final output is standard PID controller parameters, it can be directly embedded into the existing converter control platform without modifying the main circuit hardware, resulting in low implementation costs and easy acceptance and promotion by the engineering community. Attached Figure Description

[0048] Figure 1 This is a flowchart of the present invention.

[0049] Figure 2 This is a block diagram of the transfer function of the synchronous condenser excitation system of the present invention.

[0050] Figure 3 This is a diagram showing the inner and outer voltage loop structure of the grid-type converter of this invention.

[0051] Figure 4 It is the full-band of the present invention. k P , k I , k D Parameter value chart. Detailed Implementation

[0052] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings.

[0053] Example 1:

[0054] This embodiment provides a method for controlling the magnetic flux inertia of a grid-type converter based on the characteristics of a synchronous condenser, which includes the following steps:

[0055] S1: Establish a dynamic model of the synchronous condenser. The dynamic model includes a first equation consisting of the relationship between the terminal voltage, the q-axis subtransient electromotive force and the d-axis current, a second equation consisting of the dynamic process of the q-axis transient electromotive force, a third equation consisting of the dynamic process of the q-axis subtransient electromotive force, and an excitation system transfer function consisting of the input-output relationship of the excitation system.

[0056] S2: Based on the dynamic model, the transfer function relationship with the change in grid voltage amplitude as input and the change in d-axis current of the synchronous condenser as output is derived;

[0057] S3: Based on the transfer function relationship, at a preset frequency point, the proportional, integral, and differential parameters required for magnetic flux inertia support control are calculated by taking the real part of the complex number;

[0058] S4: Modify the voltage outer loop of the grid converter into a proportional, integral, and derivative control structure, and input the calculated proportional, integral, and derivative parameters to realize the magnetic flux inertia support control of the grid converter.

[0059] The following is a detailed explanation of some of the steps mentioned above:

[0060] 1. Establish a dynamic model of the synchronous condenser.

[0061] The dynamic model of the synchronous condenser consists of the following three time-domain dynamic equations for the windings and a transfer function for the excitation system:

[0062] (1)

[0063] (2)

[0064] (3)

[0065] in, This refers to the terminal voltage. This refers to the voltage on the high-voltage side of the step-up transformer, which is equivalent to the grid voltage. for Transient induced electromotive force on shaft; for Transient induced electromotive force at the shaft level; for Shaft synchronous reactance; The transient reactance is the d-axis reactance. , for Axial transient and subtransient open-circuit time constants; This refers to the transformer reactance.

[0066] For a synchronous condenser, a typical excitation system transfer function block diagram is as follows: Figure 2 As shown.

[0067] The transfer function of the synchronous condenser excitation system is given by equations (4) and (5):

[0068] (4)

[0069] (5)

[0070] in, E fd This is the excitation output voltage; It is a first-order low-pass circuit used to approximate the dynamics of a thyristor; This refers to the thyristor amplification factor. This is the thyristor operating time constant; T 1. T 2. T 3 and T All four are time constants; s For the Laplace operator; u ref This is the command value for excitation control, and it is a constant. K 0 is the proportionality coefficient, which is a constant; This is the voltage feedback coefficient.

[0071] 2. Derive the transfer function F(s) from the grid voltage amplitude to the d-axis current of the synchronous condenser.

[0072] Equation (1) can be written in the form of small signal increment Δ to obtain equation (6).

[0073] (6)

[0074] In this process, the lowercase letters in formula (1) are replaced with uppercase letters, and Δ is added in front of them.

[0075] Express equations (2) and (3) in incremental form and eliminate them. shaft transient induced electromotive force Then we can obtain equation (7).

[0076] (7)

[0077] In the formula:

[0078] (8)

[0079] (9)

[0080] According to equation (1),

[0081] (10)

[0082] but (11)

[0083] in, , , , It is the form of the disturbance quantity after a small disturbance. Let be the transfer function of the excitation system in equation (4). Substituting equations (7) and (10) into equation (6) yields the reactive current increment. With system voltage increment The transfer function is (12).

[0084] (12)

[0085] In equation (12), It is the form of the disturbance after a small disturbance. Its first term is the transient reactive current increment related to the excitation control system and the body parameters; the second term is the instantaneous reactive current increment related only to the d-axis subtransient reactance and the step-up transformer short-circuit impedance.

[0086] 3. Calculation method for PID parameters of magnetic flux inertia support control

[0087] According to equation (12), let

[0088] (13)

[0089] (14)

[0090] According to the synchronizer arrive The transfer function is used to calculate the PID parameters for magnetic flux inertia support control.

[0091] ;

[0092] ;

[0093] (15)

[0094] Where Re represents taking the real part of the complex number, lim represents taking the limit, and j is the imaginary unit. , , Representing a certain frequency value, it is a constant chosen by the individual. k P , k I , k DThese are the proportional, integral, and derivative control parameters in PID control.

[0095] 4. Modify the U-type converter based on the PID parameters calculated above. d -I d Outer Ring

[0096] The voltage outer loop of the grid-type converter was modified to a PID control structure, and the above input was used. k P , k I , k D Parameters are used to achieve flux inertia control in a grid-type converter. The voltage inner and outer loop structures of the grid-type converter are as follows: Figure 3 As shown: The outer loop PIvc(s) part of the diagram is a PID control structure, PIvc(s) = k P + k I (1 / s )+ k D s .

[0097] The above process is as follows: Figure 1 As shown.

[0098] 5. Simulation Examples

[0099] Table 1 shows the parameters of the synchronous condenser body and typical excitation control system:

[0100] Table 1. Parameters of the synchronous condenser and typical excitation system

[0101]

[0102] Note:

[0103] Drawing the full frequency band k P , k I , k D Parameter values, such as Figure 4 As shown.

[0104] Taking a frequency f = 1.00 Hz (ω = 6.28 rad / s), the PID parameters are obtained as follows:

[0105]

[0106]

[0107]

[0108] Example 2:

[0109] This embodiment provides a magnetic flux inertia control system for a grid-type converter based on the characteristics of a synchronous condenser. The system can implement all the processes described above.

[0110] A grid-type converter flux inertia control system based on synchronous condenser characteristics includes:

[0111] 1. Model building module, used to establish the dynamic model of synchronous condenser. The dynamic model includes a first equation consisting of the relationship between terminal voltage, q-axis subtransient electromotive force and d-axis current, a second equation consisting of the dynamic process of q-axis transient electromotive force, a third equation consisting of the dynamic process of q-axis subtransient electromotive force, and an excitation system transfer function consisting of the input-output relationship of the excitation system.

[0112] II. Function derivation module, used to derive the transfer function relationship based on the dynamic model, with the change in grid voltage amplitude as input and the change in d-axis current of the synchronous condenser as output;

[0113] 3. Parameter calculation module, which is used to calculate the proportional, integral and differential parameters required for magnetic flux inertia support control at a preset frequency point by taking the complex real part based on the transfer function relationship.

[0114] IV. Controller configuration and execution module, used to transform the voltage outer loop of the grid-type converter into a proportional, integral, and derivative control structure, and input the calculated proportional, integral, and derivative parameters to realize the magnetic flux inertia support control of the grid-type converter.

[0115] In specific implementation, the working principle, control process and technical effect of the magnetic flux inertia control system for grid-type converter based on the characteristics of synchronous condenser provided in this embodiment of the invention are the same as the magnetic flux inertia control method for grid-type converter based on the characteristics of synchronous condenser in the above embodiment, and will not be repeated here.

[0116] Example 3:

[0117] This embodiment provides an electronic device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements a magnetic flux inertia control method for a grid-type converter based on the characteristics of a synchronous condenser, as described in any embodiment of the present invention.

[0118] Example 4

[0119] This embodiment provides a computer-readable storage medium storing a computer program thereon. When the computer program is executed by a processor, it implements a magnetic flux inertia control method for a grid-type converter based on the characteristics of a synchronous condenser, as described in any embodiment of the present invention.

[0120] Those skilled in the art will recognize that the units and algorithm steps described in the embodiments disclosed in this invention can be implemented using electronic hardware, computer software, or a combination of electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0121] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0122] In the several embodiments provided in this application, any function, if implemented as a software functional unit and sold or used as an independent product, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, essentially, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0123] The above-described method, system, and device for controlling the flux inertia of a grid-type converter based on the characteristics of a synchronous condenser are specific embodiments of the present invention, demonstrating the substantial features and progress of the present invention. Equivalent modifications can be made to them according to actual usage needs, under the guidance of the present invention, and all such modifications are within the scope of protection of this solution.

Claims

1. A method for magnetic flux inertia control of a grid-forming converter based on synchronous phase modifier characteristics, characterized by Includes the following steps: 1) Establish a dynamic model of the synchronous condenser. The dynamic model includes a first equation consisting of the relationship between the terminal voltage, the q-axis subtransient electromotive force and the d-axis current, a second equation consisting of the dynamic process of the q-axis transient electromotive force, a third equation consisting of the dynamic process of the q-axis subtransient electromotive force, and an excitation system transfer function consisting of the input-output relationship of the excitation system. 2) Based on the dynamic model, the transfer function relationship with the change in grid voltage amplitude as input and the change in d-axis current of the synchronous condenser as output is derived; 3) Based on the transfer function relationship, at a preset frequency point, by taking the real part of the complex number, the proportional, integral, and differential parameters required for magnetic flux inertia support control are calculated; 4) Modify the voltage outer loop of the grid converter into a proportional, integral, and derivative control structure, and input the calculated proportional, integral, and derivative parameters to realize the magnetic flux inertia support control of the grid converter.

2. The method of claim 1, wherein the method is characterized by: The excitation system transfer function in step 1) has a numerator containing the product of the excitation system steady-state gain and two first-order leading elements, and a denominator containing the product of a first-order lagging element and two first-order inertial elements; the output voltage of the excitation system is obtained by passing the difference between the terminal voltage and the reference voltage through the transfer function and taking the negative sign.

3. The method of claim 1, wherein the method is characterized by: The transfer function in step 2) is F(s) + K; where F(s) is the s-domain transfer function derived from the synchronous condenser dynamic model, and K is a constant calculated based on the d-axis subtransient reactance and transformer reactance.

4. The method of claim 3, wherein the method is characterized by: The transfer function relationship in step 2) is formed by adding a fractional term and a constant term. The numerator of the fractional term includes a differential term related to the difference between the d-axis transient and subtransient reactances and the transient time constant, and an algebraic term related to the d-axis synchronous reactance, subtransient reactance, and excitation system transfer function. The denominator includes a second-order term related to multiple reactance parameters and time constants, and a term related to the d-axis synchronous reactance, transformer reactance, and excitation system transfer function. The fraction as a whole is divided by the sum of the d-axis subtransient reactance and the transformer reactance. The constant term is the negative reciprocal of the sum of the d-axis subtransient reactance and the transformer reactance.

5. The method of claim 4, wherein the method is a method of magnetic flux inertia control for a grid-forming converter based on the characteristics of a synchronous phase modifier. The proportional parameter in step 3) is calculated as follows: the sum of the fractional term and a constant term is taken as the complex real part at the first preset frequency; the integral parameter is calculated as follows: the sum of the fractional term and the constant term is multiplied by the complex frequency variable, and the complex real part is taken at the second preset frequency; the differential parameter is calculated as follows: the sum of the fractional term and the constant term is divided by the complex frequency variable, and the complex real part is taken at the third preset frequency; wherein, the constant term is the negative reciprocal of the sum of the d-axis subtransient reactance and the transformer reactance.

6. The method of claim 1, wherein the method is a method of magnetic flux inertia control for a grid-forming converter based on the characteristics of a synchronous phase modifier. In step 4), the voltage outer loop control structure of the grid converter has an output consisting of the sum of a proportional term, an integral term, and a derivative term. The proportional term is the proportional parameter, the integral term is the integral parameter divided by the complex frequency variable, and the derivative term is the derivative parameter multiplied by the complex frequency variable.

7. A magnetic flux inertia control system for a grid-type converter, characterized in that, The system is used to execute the flux inertia control method for a grid-type converter based on the characteristics of a synchronous condenser as described in any one of claims 1-6, the system comprising: The model building module is used to establish a dynamic model of the synchronous condenser. The dynamic model includes a first equation consisting of the relationship between the terminal voltage, the q-axis subtransient electromotive force and the d-axis current, a second equation consisting of the dynamic process of the q-axis transient electromotive force, a third equation consisting of the dynamic process of the q-axis subtransient electromotive force, and an excitation system transfer function consisting of the input-output relationship of the excitation system. The function derivation module is used to derive the transfer function relationship based on the dynamic model, with the change in grid voltage amplitude as input and the change in d-axis current of the synchronous condenser as output. The parameter calculation module is used to calculate the proportional, integral, and differential parameters required for magnetic flux inertia support control at a preset frequency point by taking the complex real part based on the transfer function relationship. The controller configuration and execution module is used to transform the voltage outer loop of the grid-type converter into a proportional, integral, and derivative control structure, and input the calculated proportional, integral, and derivative parameters to realize the magnetic flux inertia support control of the grid-type converter.

8. The magnetic flux inertia control system according to claim 7, characterized in that: The excitation system transfer function defined in the model construction module has a numerator containing the product of the excitation system steady-state gain and two first-order leading elements, and a denominator containing the product of a first-order lag element and two first-order inertial elements; the output voltage of the excitation system is obtained by passing the difference between the terminal voltage and the reference voltage through the transfer function and taking the negative sign. The transfer function relationship is composed of a fractional term and a constant term. The numerator of the fractional term includes a differential term related to the difference between the d-axis transient and subtransient reactances and the transient time constant, and an algebraic term related to the d-axis synchronous reactance, subtransient reactance, and excitation system transfer function. The denominator includes a second-order term related to multiple reactance parameters and time constants, and a term related to the d-axis synchronous reactance, transformer reactance, and excitation system transfer function. The fraction as a whole is divided by the sum of the d-axis subtransient reactance and the transformer reactance. The constant term is the negative reciprocal of the sum of the d-axis subtransient reactance and the transformer reactance.

9. The magnetic flux inertia control system according to claim 8, characterized in that: The parameter calculation module is configured as follows: The proportional parameter is calculated as follows: the sum of the fractional term and the constant term is taken as the complex real part at the first preset frequency; The integral parameter is calculated as follows: the sum of the fractional term and the constant term is multiplied by the complex frequency variable, and the real part of the complex number is taken at the second preset frequency. The differential parameter is calculated as follows: the sum of the fractional term and the constant term is divided by the complex frequency variable, and the real part of the complex number is taken at the third preset frequency. The constant term is the negative reciprocal of the sum of the d-axis subtransient reactance and the transformer reactance; In the controller configuration and execution module, the voltage outer loop control structure of the grid-type converter has an output consisting of the sum of a proportional term, an integral term, and a derivative term. The proportional term is the proportional parameter, the integral term is the integral parameter divided by the complex frequency variable, and the derivative term is the derivative parameter multiplied by the complex frequency variable.

10. A computer device, characterized in that: The device includes one or more processors and one or more memories, wherein at least one piece of program code is stored in the one or more memories, and when the program code is executed by the one or more processors, it implements the magnetic flux inertia control method for a grid-type converter based on the characteristics of a synchronous condenser as described in any one of claims 1-6.

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