A discrete domain STATCOM current controller design method and system

Abstract

This application provides a discrete-domain STATCOM current controller design method and system. The method includes: establishing a discrete-domain model of the controlled object based on design factors; considering the zero steady-state error control performance of the current closed-loop system, constructing a minimum-step control closed-loop transfer function for the current closed-loop system; obtaining the STATCOM current controller's transfer function in the discrete domain based on the controlled object's discrete-domain model and the closed-loop transfer function, converting it into a differential recursive equation, and implementing it in a digital processor through programming. This application proposes a design method for a STATCOM current digital controller that avoids continuous-frequency domain design and directly designs and implements it in the discrete-frequency domain. This method can directly obtain the parameters of the digital controller based on system parameters and design requirements, is easy to implement, and can achieve good current control performance.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and in particular to a design method and system for a discrete domain STATCOM current controller. Background Technology

[0002] With the increasing penetration rate of renewable energy generation, traditional power systems face more challenges, such as voltage instability, low power factor, and increased line losses. A STATCOM (Static Synchronous Compensator) is a power electronic device used in power systems to improve power quality and enhance system stability. Connected to the grid via a power electronic converter, the STATCOM can quickly and continuously regulate reactive current and reactive power, thereby improving power system stability and power quality to meet the needs of modern power systems. Besides the main circuit design and modulation method of the STATCOM, the design of the STATCOM's current controller is crucial to achieving reactive power regulation capabilities. The control objective is to ensure that the STATCOM's output current quickly and accurately tracks the command current signal. The steady-state tracking accuracy, dynamic response speed, and compensation bandwidth of the control method directly affect the device's reactive power compensation performance.

[0003] Currently, the main methods for current control in STATCOM include proportional-integral control, proportional-resonant control, and repetitive control. These methods all involve designing the controller in the continuous frequency domain, obtaining the discrete transfer function of the controller through frequency discretization, converting it into a differential recursive formula, and then implementing it on a digital controller. Due to the processing overhead of the program, the digital controller uses a one-beat lag method for the control output. At low frequencies (typically, the switching frequency of a chained STATCOM is below 1 kHz), this control lag has a significant negative impact on control stability, and can even lead to control failure. To address this problem, a unit lag element is added during continuous frequency domain analysis. Its frequency domain characteristics are quite complex (belonging to transcendental functions), and it is generally handled using Pade approximation. This approximation is related to the control bandwidth and depends on the designer's theoretical knowledge and design experience, making it quite difficult to achieve good control performance. Furthermore, the controller designed in the continuous frequency domain needs to be discretized before it can be implemented in the DSP controller. Discretization methods for continuous domain controllers include backward difference method, bilinear transform method, zero-pole correspondence method, etc. According to digital signal processing theory, each discretization method will change the frequency characteristics of the controller, causing the actual system transfer function to deviate from the designed transfer function, thus resulting in the design performance not being well achieved.

[0004] In high-power, low-switching-frequency applications like STATCOM, conventional design methods require designers to have extensive theoretical knowledge and engineering experience; otherwise, it is difficult to design an ideal STATCOM digital controller. Summary of the Invention

[0005] The purpose of this invention is to provide a discrete domain STATCOM current controller design method and system, which aims to solve the above-mentioned problems in the prior art.

[0006] This invention provides a discrete-domain STATCOM current controller design method, comprising:

[0007] Establish a discrete domain model of the controlled object based on design factors;

[0008] Considering the zero steady-state error control performance of the current closed-loop system, construct the closed-loop transfer function for minimum-step control of the current closed-loop system;

[0009] Based on the discrete domain model of the controlled object and the closed-loop transfer function, the transfer function of the STATCOM current controller in the discrete domain is obtained, which is then transformed into a differential recursive equation and implemented in a digital processor through programming.

[0010] This invention provides a discrete-domain STATCOM current controller design system, comprising:

[0011] The first design module is used to establish a discrete domain model of the controlled object based on design factors.

[0012] The second design module is used to consider the zero steady-state error control performance of the current closed-loop system and construct the closed-loop transfer function of the minimum-step control of the current closed-loop system.

[0013] The third design module is used to obtain the transfer function of the STATCOM current controller in the discrete domain based on the discrete domain model of the controlled object and the closed-loop transfer function, convert it into a differential recursive equation, and implement it in the digital processor through programming.

[0014] This invention also provides an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the steps of the discrete domain STATCOM current controller design method described above.

[0015] This invention also provides a computer-readable storage medium storing an information transmission implementation program, which, when executed by a processor, implements the steps of the discrete-domain STATCOM current controller design method described above.

[0016] The following beneficial effects can be achieved by adopting the embodiments of the present invention: In order to solve the design problem of the current controller of STATCOM, the embodiments of the present invention propose a design method for STATCOM digital controller that avoids continuous frequency domain design and is designed and implemented directly in discrete frequency domain. The method can directly obtain the parameters of the digital controller according to the system parameters and design requirements, which is easy to implement and can obtain better current control performance. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in one or more embodiments of this specification or in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart of the discrete domain STATCOM current controller design method according to an embodiment of the present invention;

[0019] Figure 2 This is a diagram of the STATCOM control structure with state decoupling and voltage feedforward according to an embodiment of the present invention;

[0020] Figure 3 This is an equivalent control block diagram of active and reactive current according to an embodiment of the present invention;

[0021] Figure 4 This is a block diagram of the digital current control according to an embodiment of the present invention;

[0022] Figure 5 This is a schematic diagram of a discrete-domain STATCOM current controller design system according to an embodiment of the present invention. Detailed Implementation

[0023] To enable those skilled in the art to better understand the technical solutions in one or more embodiments of this specification, the technical solutions in one or more embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this specification, and not all of the embodiments. Based on one or more embodiments of this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this document.

[0024] Method Implementation Examples

[0025] According to an embodiment of the present invention, a design method for a discrete-domain STATCOM current controller is provided. Figure 1This is a flowchart of the discrete-domain STATCOM current controller design method according to an embodiment of the present invention, as shown below. Figure 1 As shown, the discrete-domain STATCOM current controller design method according to an embodiment of the present invention specifically includes:

[0026] Step S101, establishing a discrete domain model of the controlled object based on design factors, specifically including:

[0027] Considering the sampling, control time lag, and zero-order hold elements of digital control, the discrete domain transfer function of the controlled object is established as shown in Equation 1.

[0028]

[0029] Where G(z) represents the controlled object model in the discrete domain, z represents a discrete frequency domain complex variable, Z[.] represents the Z-transform of the continuous domain model, e represents the natural constant, s represents a continuous frequency domain complex variable, T represents the sampling time, L represents the filter inductance of STATCOM, and r represents the equivalent resistance of the filter inductance;

[0030] The controlled object includes a one-beat lag element, a sample-and-hold circuit, and a first-order controlled object;

[0031] Step S102, considering the zero steady-state error control performance of the current closed-loop system, construct the closed-loop transfer function of the minimum-step control of the current closed-loop system, specifically including:

[0032] The mathematical relationship between the transfer function of the STATCOM current controller, the transfer function of the current closed-loop system, and the transfer function of the controlled object is shown in Equation 2.

[0033]

[0034] Where D(z) represents the transfer function of the current controller, G(z) represents the transfer function of the controlled object, and Φ(z) represents the transfer function of the current closed-loop system;

[0035] Considering the zero steady-state error control performance of the current closed-loop system, the transfer function and error transfer function of the current closed-loop system are obtained as shown in Equation 3. The mathematical relationship between the transfer function and error transfer function of the current closed-loop system is shown in Equation 4. Combining Equations 3 and 4, the closed-loop transfer function of the current closed-loop system with the least-step control is obtained as shown in Equation 5.

[0036]

[0037] Φ e (z)=1-Φ(z) Formula 4;

[0038] Φ(z)=z -2 Formula 5;

[0039] Where, Φ e (z) represents the error transfer function of the current closed-loop system, f 11 f 21 Let z and z represent monomials in z.

[0040] Step S103: Based on the discrete domain model of the controlled object and the closed-loop transfer function, obtain the transfer function of the STATCOM current controller in the discrete domain, transform it into a differential recursive equation, and implement it in a digital processor through programming. Specifically, this includes:

[0041] Based on the discrete domain model of the controlled object and the closed-loop transfer function, and based on Equation 2, the transfer function of the STATCOM current controller in the discrete domain as shown in Equation 6 is obtained. Based on the transfer function of the current controller in the discrete domain and the input and output of the current controller, the mathematical relationship shown in Equation 7 is obtained. It is then transformed into the difference recursive equation shown in Equation 8 through inverse Z-transformation and implemented in the digital processor through programming.

[0042]

[0043] u(n)=u(n-2)+k·e(n)-k·b·e(n-1) Formula 8;

[0044] in, E(z) represents the current error signal in the control system, U(z) represents the control signal, u(n) is the current control output, u(n-2) is the control output two steps ago, e(n) is the current current error signal, e(n-1) is the current error signal of the previous step, and n represents the discrete time variable.

[0045] The following describes in detail the above-mentioned technical solutions of the present invention with reference to the specific details of the discrete domain STATCOM current controller design method in the embodiments of the present invention.

[0046] This invention proposes a design and processing method for a STATCOM current controller in the discrete frequency domain. The control structure of the STATCOM system is as follows: Figure 2 As shown, the dashed box on the left represents the controller section, and the solid box on the right represents the STATCOM model in synchronous rotating coordinates (dq coordinates). dref and I qref It is the current reference for the d-axis and q-axis, I ca , I cb and I cc The three-phase compensation current output by the STATCOM is transformed into a two-phase compensation current I in the corresponding dq coordinates after a three-phase to two-phase rotational transformation. cd and Icq After the current regulator, state decoupling and voltage feedforward are applied, the control quantity of the dq axis is generated, and then the inverse transformation is used to control the main circuit of the STATCOM.

[0047] exist Figure 2 In the control structure, if the modulation and coordinate transformation processes are considered as unit proportional elements, the control structure can be simplified to an equivalent control block diagram of active and reactive current control loops, such as... Figure 3 As shown, G id (s) and G iq (s) is a controller for active and reactive current loops. Conventional designs are performed in the continuous frequency domain. This invention proposes a method for designing in the discrete frequency domain, which achieves superior control performance compared to conventional methods and is easy to implement. The control structures for active and reactive currents are the same, and the controller design is also the same.

[0048] Considering the sampling, control one-step lag, and zero-order hold stages in the digital implementation process, the block diagrams for digital control of active and reactive current can be used. Figure 4 Description, G id (s) and G iq (s) The continuous domain controller is also transformed into a discrete z-domain controller D(z). In the controller, s represents a continuous frequency domain complex variable, and z represents a discrete frequency domain complex variable.

[0049] In the discrete frequency domain Figure 4 The controlled objects include: a one-beat-later element z -1 Sample-and-hold circuit ZOH and first-order controlled object The discrete-domain model can be represented as follows (to avoid complexity, unless otherwise specified, the transfer function mentioned below refers to the discrete-domain transfer function):

[0050]

[0051] In the formula, G(z) represents the controlled object model in the discrete domain, Z[.] represents the Z-transform of the continuous domain model, e represents the natural constant, T represents the sampling time, L represents the filter inductance of STATCOM, and r represents the equivalent resistance of the filter inductance.

[0052] The current closed-loop transfer function Φ(z) is:

[0053]

[0054] In the formula, D(z) represents the transfer function of the controller.

[0055] According to the principles of automatic control, the lag elements contained in the controlled object cannot be canceled out and must exist in the designed closed-loop transfer function. Therefore, the transfer function of the current closed-loop system has the following form:

[0056] Φ(z)=z -1 F1(z) (3);

[0057] Here, F1(z) is an undetermined polynomial in z.

[0058] According to equation (2), the expression for the controller can be written as:

[0059]

[0060] That is, the transfer function of the controller can be expressed by the current closed-loop transfer function and the transfer function of the controlled object.

[0061] The system's error transfer function Φ e (z) is:

[0062]

[0063] In the formula, R(z) represents the z-domain expression of the input signal, and Y(z) represents the expression of the output signal.

[0064] The error E(z) is:

[0065] E(z)=R(z)Φ e (z) (6);

[0066] Assuming the input is a step signal, its transfer function is:

[0067]

[0068] According to the final value theorem of the Z-transform, the steady-state error of the system is:

[0069]

[0070] According to equation (8), in order to achieve tracking without steady-state error, e(∞) approaches zero, Φ e (z) must have the following form:

[0071] Φ e (z)=(1-z -1 )F2(z) (9);

[0072] Among them, F2(z) is also an undetermined polynomial in z. Combining equation (3), in order to make the system have a faster response performance, the system's transfer function Φ(z) should have finite word length response characteristics, that is, the characteristics of an FIR filter; in order to make the system obtain zero steady-state error characteristics, the system's closed-loop error transfer function Φ e (z) has the mode of equation (9). By setting the fastest response time, Φ(z) and Φ e (z) have the same order. The method of undetermined coefficients can be used to obtain the corresponding transfer function of the STATCOM current controller. This discrete frequency domain transfer function is then transformed into a discrete time domain expression, which is a differential recursive formula, and implemented in a digital signal processor.

[0073] Specifically, Figure 4 The current control closed-loop transfer function and error transfer function are in the following forms:

[0074]

[0075] In the formula, m and n are the orders of the undetermined polynomials F1(z) and F2(z). To control speed, let m = 1 and n = 1, thus we have:

[0076]

[0077] The relationship between the closed-loop transfer function and the closed-loop error transfer function is as follows:

[0078] Φ e (z)=1-Φ(z) (12);

[0079] According to equations (11) and (12), we can obtain: f 11 =f 21 =1, the closed-loop transfer function of the minimum-cycle control of the current loop is:

[0080] Φ(z)=z -2 (13);

[0081] That is, the current closed loop has zero steady-state error control performance with a two-step lag.

[0082] According to equation (4), the expression for the current controller is:

[0083]

[0084] in, These two coefficients are related to the STATCOM's filter inductance and inductor equivalent resistance, as well as the sampling time. k and b are related to the circuit parameters and the sampling time.

[0085] The input to the current controller is the current error signal, and the output is the control signal, that is:

[0086]

[0087] After inverse z-transform, the time-domain difference recursive equation of the controller can be obtained:

[0088] u(n)=u(n-2)+k·e(n)-k·b·e(n-1) (16);

[0089] Where u(n) is the current control output, u(n-2) is the control output two steps ago, e(n) is the current error signal, e(n-1) is the current error signal of the previous step, and n represents the discrete time variable.

[0090] The entire design process involves substituting the STATCOM filter inductor and inductor equivalent resistance, as well as the sampling time, into formula (14) to obtain the discrete domain expression of the digital controller. Then, through inverse z-transformation, the differential recursive formula of the digital controller is obtained. The entire design process is very simple and clear.

[0091] System Implementation Examples

[0092] According to an embodiment of the present invention, a discrete-domain STATCOM current controller design system is provided. Figure 5 This is a schematic diagram of a discrete-domain STATCOM current controller design system according to an embodiment of the present invention, as shown below. Figure 5 As shown, the discrete-domain STATCOM current controller design system according to an embodiment of the present invention specifically includes:

[0093] The first design module 50 is used to establish a discrete domain model of the controlled object based on design factors, specifically for:

[0094] Considering the sampling, control time lag, and zero-order hold elements of digital control, the discrete domain transfer function of the controlled object is established as shown in Equation 1.

[0095]

[0096] Where G(z) represents the controlled object model in the discrete domain, z represents a discrete frequency domain complex variable, Z[.] represents the Z-transform of the continuous domain model, e represents the natural constant, s represents a continuous frequency domain complex variable, T represents the sampling time, L represents the filter inductance of STATCOM, and r represents the equivalent resistance of the filter inductance;

[0097] The controlled object includes a one-beat lag element, a sample-and-hold circuit, and a first-order controlled object;

[0098] The second design module 52 is used to consider the zero steady-state error control performance of the current closed-loop system and to construct the closed-loop transfer function for the minimum-step control of the current closed-loop system. Specifically, it is used for:

[0099] The mathematical relationship between the transfer function of the STATCOM current controller, the transfer function of the current closed-loop system, and the transfer function of the controlled object is shown in Equation 2.

[0100]

[0101] Where D(z) represents the transfer function of the current controller, G(z) represents the transfer function of the controlled object, and Φ(z) represents the transfer function of the current closed-loop system;

[0102] Considering the zero steady-state error control performance of the current closed-loop system, the transfer function and error transfer function of the current closed-loop system are obtained as shown in Equation 3. The mathematical relationship between the transfer function and error transfer function of the current closed-loop system is shown in Equation 4. Combining Equations 3 and 4, the closed-loop transfer function of the current closed-loop system with the least-step control is obtained as shown in Equation 5.

[0103]

[0104] Φ e (z)=1-Φ(z) Formula 4;

[0105] Φ(z)=z -2 Formula 5;

[0106] Where, Φ e (z) represents the error transfer function of the current closed-loop system, f 11 f 21 Let z and z represent monomials in z.

[0107] The third design module 54 is used to obtain the transfer function of the STATCOM current controller in the discrete domain based on the discrete domain model of the controlled object and the closed-loop transfer function, transform it into a differential recursive equation, and implement it in the digital processor through programming. Specifically, it is used for:

[0108] Based on the discrete domain model of the controlled object and the closed-loop transfer function, and based on Equation 2, the transfer function of the STATCOM current controller in the discrete domain as shown in Equation 6 is obtained. Based on the transfer function of the current controller in the discrete domain and the input and output of the current controller, the mathematical relationship shown in Equation 7 is obtained. It is then transformed into the difference recursive equation shown in Equation 8 through inverse Z-transformation and implemented in the digital processor through programming.

[0109]

[0110]

[0111] u(n)=u(n-2)+k·e(n)-k·b·e(n-1) Formula 8;

[0112] in, E(z) represents the current error signal in the control system, U(z) represents the control signal, u(n) is the current control output, u(n-2) is the control output two steps ago, e(n) is the current current error signal, e(n-1) is the current error signal of the previous step, and n represents the discrete time variable.

[0113] The embodiments of the present invention are system embodiments corresponding to the above method embodiments. The specific operation of each module can be understood by referring to the description of the method embodiments, and will not be repeated here.

[0114] In summary, compared with existing technologies for conventional continuous frequency domain STATCOM current controllers, the embodiments of the present invention have the following advantages:

[0115] (1) The design of the current controller of STATCOM is completed in the discrete frequency domain. The design process is simple. According to the input system parameters required by equation (10), the transfer function of the controller in the discrete domain can be obtained. Then, the discrete frequency domain is converted to the discrete time domain to obtain the differential recursive formula. This avoids the conversion process from continuous frequency domain to discrete domain in the traditional processing method. There is no distortion problem of control information. It is easy to implement by digital signal processor programming.

[0116] (2) The design of STATCOM current controller can be completed digitally, which reduces the requirements for designers' theoretical knowledge and engineering experience. The entire design process is easy to program and avoids the influence of human factors.

[0117] (3) The current controller control method of this STATCOM can achieve good control performance. It can track the fast current command without steady-state error, and can also make corresponding optimizations according to the requirements of speed and stability.

[0118] Device Example 1

[0119] This invention provides an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, performs the steps described in the method embodiment.

[0120] Device Example 2

[0121] This invention provides a computer-readable storage medium storing an information transmission implementation program, which, when executed by a processor, performs the steps described in the method embodiment.

[0122] The computer-readable storage media described in this embodiment include, but are not limited to, ROM, RAM, disk, or optical disk.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A design method for a discrete-domain STATCOM current controller, characterized in that... include: Establishing a discrete-domain model of the controlled object based on design factors specifically includes: Considering the sampling, control time lag, and zero-order hold elements of digital control, the discrete domain transfer function of the controlled object is established as shown in Equation 1. Formula 1: in, Let Z represent the model of the controlled object in the discrete domain, where z represents a discrete frequency domain complex variable, and Z[.] represents the Z-transform of the continuous domain model. Let represent the natural constant, and s represent a continuous frequency domain complex variable. Indicates the sampling time. This refers to the filter inductance of STATCOM. This represents the equivalent resistance of the filter inductor. The controlled object includes a one-beat lag element, a sample-and-hold circuit, and a first-order controlled object; Considering the zero steady-state error control performance of the current closed-loop system, the closed-loop transfer function of the minimum-phase control of the current closed-loop system is constructed, specifically including: The mathematical relationship between the transfer function of the STATCOM current controller, the transfer function of the current closed-loop system, and the transfer function of the controlled object is shown in Equation 2. Formula 2: in, The transfer function of the current controller is represented. Represents the transfer function of the controlled object. The transfer function of a current closed-loop system; Considering the zero steady-state error control performance of the current closed-loop system, the transfer function and error transfer function of the current closed-loop system are obtained as shown in Equation 3. The mathematical relationship between the transfer function and error transfer function of the current closed-loop system is shown in Equation 4. Combining Equations 3 and 4, the closed-loop transfer function of the current closed-loop system with the least-step control is obtained as shown in Equation 5. Formula 3: Formula 4: Formula 5: in, This represents the error transfer function of a current closed-loop system. , They represent about monomials; Based on the discrete domain model of the controlled object and the closed-loop transfer function, the transfer function of the STATCOM current controller in the discrete domain is obtained, which is then transformed into a differential recursive equation and implemented in a digital processor through programming.

2. The method according to claim 1, characterized in that, Based on the discrete domain model of the controlled object and the closed-loop transfer function, the transfer function of the STATCOM current controller in the discrete domain is obtained, which is then transformed into a differential recursive equation and implemented in a digital processor through programming. Specifically, this includes: Based on the discrete domain model of the controlled object and the closed-loop transfer function, and based on Equation 2, the transfer function of the STATCOM current controller in the discrete domain as shown in Equation 6 is obtained. Based on the transfer function of the current controller in the discrete domain and the input and output of the current controller, the mathematical relationship shown in Equation 7 is obtained. It is then transformed into the difference recursive equation shown in Equation 8 through inverse Z-transformation and implemented in the digital processor through programming. Formula 6: Formula 7: Formula 8: in, , , This represents the current error signal in the control system. Indicates control signal, This is the current control output. It is the control output two beats in advance. This is the current current error signal. It is the current error signal from the previous frame. Represents a discrete-time variable.

3. A discrete-domain STATCOM current controller design system, characterized in that... include: The first design module is used to establish a discrete-domain model of the controlled object based on design factors, specifically for: Considering the sampling, control time lag, and zero-order hold elements of digital control, the discrete domain transfer function of the controlled object is established as shown in Equation 1. Formula 1: in, Let Z represent the model of the controlled object in the discrete domain, where z represents a discrete frequency domain complex variable, and Z[.] represents the Z-transform of the continuous domain model. Let represent the natural constant, and s represent a continuous frequency domain complex variable. Indicates the sampling time. This refers to the filter inductance of STATCOM. This represents the equivalent resistance of the filter inductor. The controlled object includes a one-beat lag element, a sample-and-hold circuit, and a first-order controlled object; The second design module is used to consider the zero steady-state error control performance of the current closed-loop system and to construct the closed-loop transfer function for the minimum-step control of the current closed-loop system. Specifically, it is used for: The mathematical relationship between the transfer function of the STATCOM current controller, the transfer function of the current closed-loop system, and the transfer function of the controlled object is shown in Equation 2. Formula 2: in, The transfer function of the current controller is represented. Represents the transfer function of the controlled object. The transfer function of a current closed-loop system; Considering the zero steady-state error control performance of the current closed-loop system, the transfer function and error transfer function of the current closed-loop system are obtained as shown in Equation 3. The mathematical relationship between the transfer function and error transfer function of the current closed-loop system is shown in Equation 4. Combining Equations 3 and 4, the closed-loop transfer function of the current closed-loop system with the least-step control is obtained as shown in Equation 5. Formula 3: Formula 4: Formula 5: in, This represents the error transfer function of a current closed-loop system. , They represent about monomials; The third design module is used to obtain the transfer function of the STATCOM current controller in the discrete domain based on the discrete domain model of the controlled object and the closed-loop transfer function, convert it into a differential recursive equation, and implement it in the digital processor through programming.

4. The system according to claim 3, characterized in that, The third design module is specifically used for: Based on the discrete domain model of the controlled object and the closed-loop transfer function, and based on Equation 2, the transfer function of the STATCOM current controller in the discrete domain as shown in Equation 6 is obtained. Based on the transfer function of the current controller in the discrete domain and the input and output of the current controller, the mathematical relationship shown in Equation 7 is obtained. It is then transformed into the difference recursive equation shown in Equation 8 through inverse Z-transformation and implemented in the digital processor through programming. Formula 6: Formula 7: Formula 8: in, , , This represents the current error signal in the control system. Indicates control signal, This is the current control output. It is the control output two beats in advance. This is the current current error signal. It is the current error signal from the previous frame. Represents a discrete-time variable.

5. An electronic device, characterized in that, include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the steps of the discrete-domain STATCOM current controller design method as described in any one of claims 1-2.

6. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores an implementation program for information transmission, which, when executed by a processor, implements the steps of the discrete-domain STATCOM current controller design method as described in any one of claims 1-2.

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