Synchronous coordinate system phase-locked loop based on performance excitation anti-saturation control

Abstract

The invention discloses a synchronous coordinate system phase-locked loop based on performance excitation anti-saturation control. The synchronous coordinate system phase-locked loop is composed of a phase detector, a loop filter, an artificial amplitude limiter, an anti-saturation feedback loop, a voltage-controlled oscillator and a performance excitation loop. An artificial amplitude limiter is arranged between a loop filter and a voltage-controlled oscillator, so that the variation amplitude of a frequency estimator is limited, and frequency divergence caused by depth disturbance is inhibited. And meanwhile, an anti-saturation feedback loop is constructed by using a difference value between input and output of the amplitude limiter, the recovery process of an integration link is accelerated when saturation occurs, and the attraction domain of a closed-loop system is expanded. Besides, a tracking error formed by a phase estimation value of the phase-locked loop and an expected value is introduced into a performance excitation loop for adjusting the starting opportunity of anti-saturation compensation and improving the dynamic performance in different operation scenes. According to the scheme, the stable phase tracking capability can be kept in a complex electric energy environment, and the synchronization reliability of the converter is improved.

Description

Technical Field

[0001] This invention relates to the field of grid-connected control technology for power electronic devices, and specifically to a synchronous coordinate system phase-locked loop based on performance-excited anti-saturation control. Background Technology

[0002] With the continuous increase in the proportion of renewable energy connected to the grid and the deepening of power electronics in the power grid, voltage source converters play a crucial role in phase synchronization and stability control during grid-connected operation. Grid-connected voltage source converters typically rely on synchronous coordinate system phase-locked loops (PLLs) to estimate the phase of the point of common coupling voltage in real time to maintain synchronization between the grid-connected current and the grid voltage. However, traditional synchronous coordinate system PLLs are prone to phase tracking deviations under complex conditions such as grid voltage dips, imbalances, and harmonic pollution. In severe cases, this can lead to loss of system synchronization, affecting the stable operation of grid-connected devices.

[0003] Existing research aims to mitigate frequency divergence caused by faults by introducing limiters into the phase-locked loop (PLL) circuit to suppress the rate of frequency change, thereby maintaining the PLL's basic synchronization capability during faults. However, the limiter also introduces integrator saturation, resulting in significant steady-state errors and a small attraction domain during system recovery after a fault, potentially preventing the system from recovering from severe disturbances. Furthermore, under different operating conditions, the timing and amplitude of the limiter's activation significantly affect the closed-loop dynamic response; inappropriate limiter configurations can further degrade the PLL's convergence speed.

[0004] To address the stability degradation caused by saturation in the integral stage, some technical solutions propose feeding back the difference between the limiter's input and output to the loop filter to accelerate the saturation removal process. However, existing solutions mostly employ fixed anti-saturation compensation structures, which cannot dynamically adjust the compensation level based on the real-time tracking error of the phase-locked loop. This results in limited anti-saturation effectiveness under deep fault scenarios and insufficient improvement in the system's attraction domain.

[0005] In view of this, the present invention proposes a synchronous coordinate system phase-locked loop based on performance-excited anti-saturation control. Summary of the Invention

[0006] The purpose of this invention is to provide a synchronous coordinate system phase-locked loop based on performance-excited anti-saturation control, which aims to solve the problems of integrator saturation, attraction domain shrinkage, and phase synchronization instability that existing synchronous coordinate system phase-locked loops are prone to under power grid faults or long-term disturbances.

[0007] In a first aspect, the present invention provides a synchronous coordinate system phase-locked loop based on performance-excited anti-saturation control, characterized in that it comprises:

[0008] Based on the phase-locked loop (PLL) and the phase output of the PLL, the three-phase voltage at the point of common coupling (PCC) is transformed to its synchronous coordinate system using Clarke transform and Park transform to obtain the cross-axis component of the PCC voltage.

[0009] The loop filter takes the quadrature-axis component of the common connection point voltage as input, uses a low-pass filter (such as a proportional-integral controller) to filter out high-frequency components and noise in the signal, and uses the output as the input of the voltage-controlled oscillator.

[0010] An artificial limiter is placed between the loop filter and the voltage-controlled oscillator to limit the input of the voltage-controlled oscillator, i.e., the frequency estimate of the phase-locked loop.

[0011] The anti-saturation feedback loop is designed by taking the difference between the input and output of the artificial limiter. When the artificial limiter triggers saturation, the system quickly exits saturation, thereby increasing the system's attraction range.

[0012] The voltage-controlled oscillator (VCO) obtains the phase-locked loop (PLL) phase estimate by summing the PLL frequency estimate with the grid rated frequency and integrating over time.

[0013] The performance excitation circuit calculates the difference between the estimated phase value and the expected value of the phase-locked loop, uses this difference as the phase tracking error of the phase-locked loop, designs the performance excitation circuit, and adjusts the start-up timing of the anti-saturation feedback circuit.

[0014] As a preferred technical solution of the present invention, the phase detector outputs the cross-axis component of the common coupling point voltage in the synchronous rotating coordinate system. The cross-axis component is composed of the phase offset relationship between the fundamental component of the common coupling point grid voltage and the phase-locked loop phase estimate, and is superimposed with the current component corresponding to the common coupling point lead impedance and the inductance component related to the phase-locked loop output angular frequency.

[0015] The quadrature component varies with the phase-locked loop (PLL) phase estimate, thereby forming a feedback signal to the PLL phase estimate.

[0016] As a preferred technical solution of the present invention, the function of the loop filter is to stomp the quadrature-axis component of the point of common coupling voltage to zero, and the phase-locked loop phase estimate value... Theoretical value of phase with the power grid The difference The steady-state quantity will be reached; the steady-state quantity is jointly determined by the grid impedance, the grid-connected current reference value, and the direct-axis current reference value, and its expression is:

[0017] ;

[0018] The fundamental amplitude of the voltage at the point of common coupling. The rated angular frequency, This is the reference value for the quadrature-axis current. The equivalent inductance at the point of common connection, This is the reference value for the direct-axis current. This is the equivalent resistance at the point of common coupling. Therefore, the loop filter not only filters out high-frequency disturbances and keeps the error signal stable, but also establishes a fixed offset relationship between the phase-locked loop phase estimate and the grid phase under steady-state conditions.

[0019] As a preferred technical solution of the present invention, the artificial limiter is disposed between the loop filter and the voltage-controlled oscillator to limit the frequency estimation value of the phase-locked loop; and the artificial limiter adopts a symmetrical structure, so that when the input exceeds the preset fixed limit value, the output keeps the boundary value unchanged.

[0020] As a preferred technical solution of the present invention, the anti-saturation feedback loop utilizes the difference between the input and output of the artificial limiter to construct two feedback terms with clear directions:

[0021] The first term is fed back to the input of the loop filter;

[0022] The second item is the integral state quantity fed back to the PI controller in the loop filter.

[0023] As a preferred technical solution of the present invention, the anti-saturation feedback loop adopts a static anti-saturation structure, and its feedback parameter is a fixed binary column vector. The feedback parameter is obtained by solving a set of optimization problems based on linear matrix inequalities. The optimization problem is determined based on the small-signal model characteristics of the system at the steady-state operating point, and is obtained by solving the system stability constraints, amplitude limiting constraints, and state consistency constraints in a joint constraint solution.

[0024] As a preferred technical solution of the present invention, the performance excitation circuit obtains the phase tracking error by comparing the phase estimate of the phase-locked loop with the corresponding desired phase, and introduces the phase tracking error into the input link of the artificial limiter after processing with a fixed proportional relationship, so as to adjust the participation timing of the anti-saturation feedback circuit.

[0025] The phase tracking error, as one of the system state variables, together with the integral state in the loop filter, constitutes the internal state description of the phase-locked loop, enabling the performance excitation circuit to participate in regulation when the system deviates from steady-state operating conditions.

[0026] As a preferred technical solution of the present invention, the state variable of the phase-locked loop system is a binary column vector. , This refers to the phase tracking error of the phase-locked loop. This is the output of the integrator in the PI controller.

[0027] As a preferred technical solution of the present invention, the dynamic characteristics of the phase-locked loop system are described by its differential equation model, which couples the system state variables, the difference generated by the anti-saturation feedback loop, and the system nonlinear terms; the nonlinear terms include static disturbance terms from the power grid side.

[0028] As a preferred technical solution of the present invention, the input of the artificial limiter is subject to the combined effects of the system state variables, the difference generated by the anti-saturation feedback loop, and the system nonlinear terms, wherein the weight of each effect is determined by the anti-saturation parameter vector, the performance excitation matrix, and other coefficient matrices.

[0029] The technical effects and advantages provided by the present invention in the above technical solution are as follows:

[0030] This invention suppresses frequency divergence caused by deep grid disturbances by setting an artificial limiter between the loop filter and the voltage-controlled oscillator (VCO) to limit the instantaneous change in the frequency estimate. Because the rate of frequency change is constrained, the integrator of the VCO will not continuously accumulate deviations during faults, thus providing controllable initial conditions for subsequent phase recovery. Furthermore, the difference between the limiter's input and output is used to construct an anti-saturation feedback loop. When the limiter enters saturation, compensation is applied to the filter output, allowing the accumulated offset of the integrator to be released quickly, thereby expanding the system's attraction domain and shortening the synchronization recovery time. In addition, the difference between the phase-locked loop's phase estimate and the expected value is used as the tracking error input performance trigger loop, ensuring that the initiation timing of anti-saturation compensation corresponds to the disturbance intensity. Compensation is triggered earlier when the error increases, thus maintaining a stable phase convergence process under strong disturbance scenarios. Through the combined effect of these three improvements, this invention can maintain high phase tracking stability and improve the grid-connected reliability of the converter under voltage dips, imbalances, and long-term disturbances. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0032] Figure 1 This is a schematic diagram of the grid-type voltage source converter of the present invention;

[0033] Figure 2 This is a control block diagram of the improved synchronous coordinate system phase-locked loop based on performance-excited anti-saturation control according to the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0035] Throughout the accompanying drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions. The described embodiments are only a part of the embodiments of this application, not all of them. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0036] Example 1

[0037] Please see Figure 2 As shown, this embodiment provides a synchronous coordinate system phase-locked loop based on performance-excited anti-saturation control, including a phase detector, loop filter, artificial limiter, anti-saturation feedback loop, voltage-controlled oscillator, and performance-excited loop. The signal flow and physical connection relationship between the components form a frequency synchronization control link.

[0038] The phase detector performs Clark and Park transformations on the three-phase voltages at the point of common coupling (PCC) based on the phase estimate output from the previous sampling cycle of the PLL. This transforms the three-phase stationary coordinate system voltages to a synchronous rotating coordinate system. The transformed quadrature-axis component serves as the PLL's error signal, characterizing the shift between the grid phase and the currently estimated phase. The quadrature-axis component of the PCC voltage output by the phase detector directly enters the subsequent loop filter and is not involved in the calculations of other branches.

[0039] The loop filter takes the quadrature-axis component of the common coupling point voltage as input and adopts a proportional-integral controller to form a low-pass filter structure, which suppresses high-frequency disturbance components and measurement noise in the signal. The proportional term and integral term constitute the adjustment amount of the instantaneous response and the cumulative offset, respectively. The two are superimposed to form the original frequency offset, and the output result is used as the input of the voltage-controlled oscillator.

[0040] An artificial limiter, positioned between the loop filter and the voltage-controlled oscillator (VCO), limits the amplitude of the frequency offset input, keeping the frequency variation within a fixed range. The artificial limiter employs symmetrical amplitude boundaries and uses a piecewise function structure to ensure that the input signal maintains the boundary value when it exceeds the boundary. The artificial limiter only changes the amplitude, not the signal phase, and does not introduce additional dynamic elements, thus maintaining the determinism of the control link and limiting the input of the VCO, i.e., the frequency estimate of the phase-locked loop.

[0041] The anti-saturation feedback loop is used to detect whether the manual limiter has entered a saturation state. The difference between the input and output of the manual limiter is taken as the feedback value. Based on the feedback value, a reverse correction link is constructed to make the system quickly exit saturation when the manual limiter triggers saturation, thereby increasing the attraction domain of the system.

[0042] Specifically, the difference between the input and output of the manual limiter is calculated for each sampling period to obtain the amplitude difference. When the manual limiter is working within the limited range, the amplitude difference is zero. When the output of the manual limiter reaches the upper or lower limit boundary, the amplitude difference is non-zero.

[0043] The anti-saturation feedback loop constructs two feedback terms with clear directions based on the amplitude difference. One term is fed back to the input of the loop filter, and the other term is fed back to the output of the loop filter, so that the loop filter can simultaneously correct the input error signal and the integral state quantity in reverse when saturation occurs.

[0044] Therefore, after entering the saturation region, the loop filter can continuously reduce the accumulated offset, allowing the limiter to recover to the non-saturation region within a finite sampling period, thereby reducing the saturation duration and expanding the attraction domain of the control system. During this process, the anti-saturation feedback loop does not change the integral structure of the voltage-controlled oscillator; offset correction is achieved solely through the fixed connection between the amplitude difference and the filter structure.

[0045] The voltage-controlled oscillator (VCO) sums the frequency offset output from the artificial limiter with the rated angular frequency of the power grid, and performs time integration on the synthesized result to obtain the phase estimate for the next sampling period. The integration process uses a fixed step size to maintain the deterministic phase update rate. The VCO does not receive direct input from the anti-saturation feedback loop; its input comes only from the limiter, thus maintaining the structural separation between the integration link and the nonlinear compensation link.

[0046] The performance excitation circuit is used to form the starting condition of the anti-saturation feedback circuit, realizing the segmented offset adjustment of the phase-locked loop under different operating conditions.

[0047] Specifically, the phase estimate output by the voltage-controlled oscillator is compared with the reference phase on a sample-by-sample basis, and the difference is calculated as the phase tracking error. The performance excitation circuit constructs a performance excitation quantity based on the magnitude of this phase tracking error, ensuring that the performance excitation quantity is generated only when the phase tracking error is outside a specified range. This performance excitation quantity is input to the anti-saturation feedback circuit through a fixed structure, enabling the anti-saturation feedback circuit to enter the working state earlier when the phase error increases, and to remain unaffected when the phase error is within the steady-state range.

[0048] The performance excitation loop does not change the computational structure of the loop filter or voltage-controlled oscillator. Its output is only used as the timing control quantity for the anti-saturation feedback loop, enabling the system to obtain a faster phase recovery capability under deep disturbances and maintain the static nature of the anti-saturation loop during steady state, thereby forming an offset adjustment mechanism with interval segmentation characteristics.

[0049] In the phase detector of this embodiment, the point of common coupling voltage is the grid connection voltage of the voltage source converter after passing through the filter inductor, i.e. Figure 1 The three-phase voltage shown , , The phase estimate of the three-phase voltage over one sampling period in the phase-locked loop. The following steps, involving Clarke transformation and Parker transformation, yield the direct-axis components in the synchronously rotating coordinate system. With cross axis components Among them, the cross-axis component It reflects the offset between the phase of the voltage vector at the point of common coupling and the phase estimated by the phase-locked loop (PLL), and is the phase error signal of the PLL. The quadrature-axis component of the point of common coupling voltage... The expression is:

[0050] ;

[0051] in: Indicates the amplitude of the fundamental voltage of the power grid. Indicates the actual phase of the grid voltage. This is the phase estimate obtained from the previous sampling period of the phase-locked loop; , These are the impedance and inductance of the common connection point lead, respectively. , Reference values ​​for the current component and inductance component in a synchronously rotating coordinate system; This is the estimated angular frequency of the phase-locked loop output.

[0052] This can be understood as the cross-axis component. Directly dependent on the phase-locked loop phase estimate This provides real-time feedback on the phase estimation error of the phase-locked loop.

[0053] In the loop filter of this invention, the function of the loop filter is to filter out high-frequency components and noise in the signal, while simultaneously filtering out the quadrature-axis component of the point of common coupling voltage. Calmed to zero. The loop filter employs a proportional-integral (PI) structure. The proportional element provides instantaneous error signal adjustment, while the integral element compensates for the accumulated offset, thereby filtering out high-frequency components and noise in the quadrature-axis component and maintaining stable low-frequency characteristics of the input signal. The relationship between the loop filter output and the quadrature-axis component remains deterministic. When the quadrature-axis component is adjusted to near zero, the voltage vector at the point of common coupling can be considered to be aligned with the phase-locked loop (PLL) estimated phase.

[0054] The quadrature axis component of the voltage at the point of common coupling When fully adjusted and brought to steady-state near zero, the phase estimate of the phase-locked loop is... Theoretical value of phase with the power grid The difference The steady-state quantity will be reached. This steady-state quantity is jointly determined by the grid impedance, the grid-connected current reference value, and the direct-axis current reference value, and its expression is:

[0055] ;

[0056] in: The fundamental amplitude of the voltage at the point of common coupling. The rated angular frequency, This is the reference value for the quadrature-axis current. The equivalent inductance at the point of common connection, This is the reference value for the direct-axis current. This is the equivalent resistance at the point of common coupling. Therefore, the loop filter not only filters out high-frequency disturbances and keeps the error signal stable, but also establishes a fixed offset relationship between the phase-locked loop phase estimate and the grid phase under steady-state conditions.

[0057] In this embodiment of the invention, the manual limiter is positioned between the loop filter and the voltage-controlled oscillator (VCO) to limit the amplitude of the frequency offset, keeping the frequency adjustment within a fixed range. The upper and lower limit boundaries of the manual limiter are symmetrical, allowing the limiter to be set to... When the frequency offset input from the loop filter... When the input exceeds this symmetrical range, the manual limiter outputs the boundary value; when the input is within the range, the manual limiter maintains the input unchanged. The mathematical expression for the manual limiter is:

[0058] ;

[0059] As can be seen from the above structure, the artificial limiter does not change the signal phase or introduce other dynamic factors. It only truncates the signal when the amplitude exceeds the boundary, so that the frequency offset of the loop output is kept within a controllable range before entering the voltage-controlled oscillator, providing a clear saturation criterion for the subsequent anti-saturation feedback loop.

[0060] In the anti-saturation feedback loop of this embodiment of the invention, the anti-saturation feedback loop is used to form a reverse correction path when the manual limiter enters the saturation state, enabling the system to exit the saturation range within a finite time. The anti-saturation feedback loop first converts the input quantity of the manual limiter... The amplitude difference is calculated by subtracting the output of the manual limiter from the amplitude difference. When the limiter is within its range, the amplitude difference is zero; when the limiter is saturated, the amplitude difference is not zero. The amplitude difference provides clear information about the degree of saturation. This embodiment employs a static anti-saturation design, and its feedback parameters... This can be obtained by solving the following optimization problem:

[0061] ;

[0062] In the formula, min represents the minimization operation; These are scalar variables to be optimized, used to characterize system performance constraints. Let Q be a positive real number; Q>0 indicates that matrix Q is a symmetric positive definite matrix, U>0 indicates that matrix U is a symmetric positive definite matrix, and Y and Z are auxiliary matrix variables to be solved. Under the condition of satisfying several linear matrix inequalities, solve a set of matrix variables and scalar variables to minimize the objective function.

[0063] ;

[0064] In the formula, Represents a block matrix composed of block elements; This indicates that the matrix is ​​a positive semi-definite matrix; For the multicellular model The parameter vector corresponding to each vertex; parameter vector transpose; is the Lyapunov matrix, used to construct the quadratic Lyapunov function of the system.

[0065] ;

[0066] In this formula, a value less than zero indicates a strictly negative definite matrix; This is the coefficient matrix of the small-signal model of the system at the steady-state operating point. Here is the state matrix of the closed-loop system. For matrix transpose; The system matrix corresponding to the disturbance input channel; This is the system matrix corresponding to the channels of uncertain parameters or auxiliary variables; The output matrix is ​​related to the control input; This is a direct transfer matrix between the control input and the uncertain variable; for matrix, For auxiliary matrix variables, It is the identity matrix; This is a performance constraint term used to limit the gain relationship between control and disturbance.

[0067] ;

[0068] In the formula, Given a positive scalar parameter, used to limit the upper bound of the control gain or system output energy; this formula is a positive semi-definite matrix.

[0069] In the performance excitation circuit of the embodiment of the present invention, the difference between the phase-locked loop phase estimate and the expected value is used as the phase tracking error of the phase-locked loop, and fed back to the input of the artificial limiter through the gain matrix F to adjust the start-up timing of the anti-saturation feedback circuit.

[0070] In embodiments of the present invention, let For system state variables, This refers to the phase tracking error of the phase-locked loop. The output of the integrator in the PI controller; the static disturbance term from the grid side is incorporated into the nonlinear term:

[0071] ;

[0072] in: and These are the equivalent resistance and inductance of the common connection point, respectively. , These are reference values ​​for the direct-axis and quadrature-axis currents. The rated angular frequency, The fundamental voltage amplitude of the power grid. , For proportional-integral parameters, This is the difference between the input and output of the manual limiter. ;

[0073] Based on the above definitions, this invention introduces an anti-saturation parameter vector and a performance excitation matrix to obtain a small-signal state-space model of the phase-locked loop: The system modeling is as follows:

[0074] ;

[0075] in: Represents the state vector The rate of change of state differentiated with respect to time; Represents the system matrix related to the proportional element; Represents the system matrix related to the integration or compensation process; This indicates the degree of saturation of the diagonal matrix representing the anti-saturation parameter; The performance excitation matrix represents the intensity of the excitation that regulates the performance of the system. This represents the state selection matrix from which a specified component is extracted from the state vector; This represents the state selection matrix for extracting another specified component from the state vector; Represents a vector of auxiliary variables related to saturation; This represents the external disturbance vector.

[0076] ;

[0077] in: Indicates the control output quantity; This represents the output matrix constructed from the state matrix corresponding to the proportional element; This represents the output matrix constructed from the state matrix corresponding to the integration or compensation stage. This represents the projection of the disturbance vector onto the specified state channel.

[0078] The coefficient matrices in the formula are as follows:

[0079] ;

[0080] ;

[0081] ;

[0082] ;

[0083] ;

[0084] The above model gives the coupling relationship between the performance excitation loop, the anti-saturation feedback loop and the artificial limiter under a unified state space framework, clarifies the mathematical forms of state variables, input variables and nonlinear terms, so that the dynamic characteristics and stability analysis of the present invention have a computable basis, and ensures that performance excitation and anti-saturation compensation work together within the same control structure.

[0085] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A synchronous coordinate system phase-locked loop based on performance-excited anti-saturation control, characterized in that, include: Based on the phase-locked loop (PLL) and the phase output of the PLL, the three-phase voltage at the point of common coupling (PCC) is transformed to its synchronous coordinate system using Clarke transform and Park transform to obtain the cross-axis component of the PCC voltage. The loop filter takes the quadrature-axis component of the common connection point voltage as input, uses a low-pass filter to filter out high-frequency components and noise in the signal, and uses the output as the input of the voltage-controlled oscillator. An artificial limiter is placed between the loop filter and the voltage-controlled oscillator to limit the input of the voltage-controlled oscillator, i.e., the frequency estimate of the phase-locked loop. The anti-saturation feedback loop is designed by taking the difference between the input and output of the artificial limiter. When the artificial limiter triggers saturation, the system quickly exits saturation, thereby increasing the system's attraction range. The voltage-controlled oscillator (VCO) obtains the phase-locked loop (PLL) phase estimate by summing the PLL frequency estimate with the grid rated frequency and integrating over time. The performance excitation circuit calculates the difference between the estimated phase value and the expected value of the phase-locked loop, uses this difference as the phase tracking error of the phase-locked loop, designs the performance excitation circuit, and adjusts the start-up timing of the anti-saturation feedback circuit.

2. The synchronous coordinate system phase-locked loop based on performance-excited anti-saturation control according to claim 1, characterized in that, The phase detector outputs the cross-axis component of the common coupling point voltage in the synchronous rotating coordinate system. The cross-axis component is composed of the phase shift relationship between the fundamental component of the common coupling point grid voltage and the phase-locked loop phase estimate, and is superimposed with the current component corresponding to the common coupling point lead impedance and the inductance component related to the phase-locked loop output angular frequency. The quadrature component varies with the phase-locked loop (PLL) phase estimate, thereby forming a feedback signal to the PLL phase estimate.

3. A synchronous coordinate system phase-locked loop based on performance-excited anti-saturation control according to claim 2, characterized in that, The function of the loop filter is to stomp the quadrature-axis component of the point of common coupling voltage to zero, and the phase-locked loop phase estimate. Theoretical value of phase with the power grid The difference The steady-state quantity will be reached; the steady-state quantity is jointly determined by the grid impedance, the grid-connected current reference value, and the direct-axis current reference value, and its expression is: ； in: The fundamental amplitude of the voltage at the point of common coupling. The rated angular frequency, This is the reference value for the quadrature-axis current. The equivalent inductance at the point of common connection, This is the reference value for the direct-axis current. Equivalent resistance at the point of common coupling; The loop filter removes high-frequency disturbances and keeps the error signal stable, forming a fixed offset relationship between the phase-locked loop phase estimate and the grid phase under steady-state conditions.

4. A synchronous coordinate system phase-locked loop based on performance-excited anti-saturation control according to claim 3, characterized in that, The artificial limiter is positioned between the loop filter and the voltage-controlled oscillator to limit the frequency estimate of the phase-locked loop; and the artificial limiter adopts a symmetrical structure, so that when the input exceeds the preset fixed limit value, the output maintains the boundary value unchanged.

5. A synchronous coordinate system phase-locked loop based on performance-excited anti-saturation control according to claim 4, characterized in that, The anti-saturation feedback loop utilizes the difference between the input and output of the artificial limiter to construct two feedback terms with clearly defined directions: The first term is fed back to the input of the loop filter; The second item is the integral state quantity fed back to the PI controller in the loop filter.

6. A synchronous coordinate system phase-locked loop based on performance-excited anti-saturation control according to claim 5, characterized in that, The anti-saturation feedback loop adopts a static anti-saturation structure, and its feedback parameter is a fixed binary column vector. The feedback parameter is obtained by solving a set of optimization problems based on linear matrix inequalities. The optimization problem is determined based on the small-signal model characteristics of the system at the steady-state operating point, and is obtained by solving the system stability constraints, amplitude limiting constraints, and state consistency constraints in a joint constraint solution.

7. A synchronous coordinate system phase-locked loop based on performance-excited anti-saturation control according to claim 6, characterized in that, The performance excitation circuit obtains the phase tracking error by comparing the phase estimate of the phase-locked loop with the corresponding desired phase, and then introduces the phase tracking error into the input link of the artificial limiter after processing it with a fixed proportional relationship, so as to adjust the participation timing of the anti-saturation feedback circuit. The phase tracking error, as one of the system state variables, together with the integral state in the loop filter, constitutes the internal state description of the phase-locked loop, enabling the performance excitation circuit to participate in regulation when the system deviates from steady-state operating conditions.

8. A synchronous coordinate system phase-locked loop based on performance-excited anti-saturation control according to claim 7, characterized in that, The state variables of the phase-locked loop system are a binary column vector. , This refers to the phase tracking error of the phase-locked loop. This is the output of the integrator in the PI controller.

9. A synchronous coordinate system phase-locked loop based on performance-excited anti-saturation control according to claim 8, characterized in that, The dynamic characteristics of the phase-locked loop system are described by its differential equation model, which couples the system state variables, the difference generated by the anti-saturation feedback loop, and the system nonlinear terms; the nonlinear terms include static disturbance terms from the grid side.

10. A synchronous coordinate system phase-locked loop based on performance-excited anti-saturation control according to claim 1, characterized in that, The input of the artificial limiter is affected by the system state variables, the difference generated by the anti-saturation feedback loop, and the system nonlinear terms. The weights of each effect are determined by the anti-saturation parameter vector, the performance excitation matrix, and other coefficient matrices.

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