Method, system, equipment and medium for improving stability of grid-connected electric energy conversion system

Abstract

The invention discloses a method, a system, equipment and a medium for improving the stability of a grid-connected electric energy conversion system, and belongs to the technical field of grid-connected stability control, and the method comprises the steps: obtaining a state decoupling component through combining with a synchronous reference signal decoupling interface parameter; calculating a dynamic power compensation value based on virtual energy shaping parameter weighted differential fluctuation and coupling correlation; injecting the compensation value into a tracking loop as self-adaptive damping, correcting deviation and updating a synchronous reference signal; a pulse is generated to drive the system. The system comprises a state decoupling analysis module, a dynamic compensation calculation module, an operation characteristic reconstruction module and a modulation driving control module. According to the invention, by constructing the magnetic energy change logic, simulating the energy throughput characteristics of the synchronous machine rotor, self-adapting to the impedance change of the power grid and the working condition of the weak grid, and compensating the virtual inertia and damping in real time, the dynamic response speed is considered while the power oscillation is suppressed, and the robustness of the system is improved.

Description

A method, system, device, and medium for improving the stability of grid-connected power conversion systems. Technical Field

[0001] This invention relates to the field of grid-connected stability control technology, and specifically to a method, system, device, and medium for improving the stability of grid-connected power conversion systems. Background Technology

[0002] With a high proportion of renewable energy sources, such as wind and solar power, being integrated into the power system, the rotational inertia provided by traditional synchronous generators is continuously decreasing, leading to a significant drop in the overall system inertia level and forming a typical low-inertia grid-connected power conversion system. Maintaining the frequency and dynamic stability of low-inertia grid-connected power conversion systems has become a core challenge in building new power systems. As a key interface for renewable energy grid integration, the control strategy of power electronic converters plays a decisive role in system stability.

[0003] In low-inertia grid-connected power conversion systems, the inherent stability margin is reduced, and the sensitivity to disturbances increases dramatically. Especially under common operating conditions such as line switching, topology changes after faults, and short-circuit ratio fluctuations, the system is prone to power oscillations, frequency instability, and even collapse due to insufficient damping. Existing converter-based stability enhancement technologies, such as virtual synchronous generator technology, mainly provide virtual inertia support by simulating the rotor motion equations of a synchronous machine. However, these technologies have significant limitations in dealing with complex and variable grid conditions. First, the introduced virtual inertia often comes at the cost of sacrificing dynamic response speed, making it difficult to achieve an ideal balance between inertia support and rapid response. Second, existing damping enhancement strategies with fixed damping coefficients or additional control based on specific models are insufficiently robust to changes in system parameters, especially grid impedance changes, making it difficult to compensate for current energy losses caused by grid impedance changes in real time and effectively. Their stability assurance capability is limited under SCR fluctuations or weak grid conditions. Finally, existing methods still face challenges in achieving smooth and stable switching between grid-connected and off-grid modes. Summary of the Invention

[0004] In view of the above-mentioned problems, the present invention provides a method, system, device and medium for improving the stability of grid-connected power conversion systems.

[0005] Therefore, the technical problem solved by this invention is that high-proportion renewable energy grid-connected systems are prone to power oscillations or even instability due to lack of inertia and insufficient damping under grid impedance fluctuations and weak grid conditions. Existing control strategies are difficult to balance inertia support strength and dynamic response speed, and have poor robustness to grid parameter perturbations, making it difficult to compensate for transient energy losses in real time.

[0006] To address the aforementioned technical problems, this invention provides the following technical solution: a method for improving the stability of a grid-connected power conversion system, comprising: acquiring the operating reference command and interface operating parameters of the grid-connected power conversion system; decoupling the interface operating parameters by combining a real-time feedback synchronization reference signal; analyzing to obtain a state decoupling component characterizing the dynamic features of the grid-connected power conversion system; invoking a transient energy compensation model, introducing virtual energy shaping parameters to weight the direct-axis differential fluctuation and orthogonal-axis coupling correlation of the state decoupling component, simulating the transient energy throughput mechanism under grid impedance disturbance to quantify losses, and dynamically calculating a dynamic power compensation value; operating a response characteristic reconstruction model, mapping the dynamic power compensation value as an adaptive damping term injected into the tracking loop of the operating reference command, correcting the power tracking deviation to reshape the equivalent inertia support and voltage dynamic stiffness of the grid-connected power conversion system, and updating the synchronization reference signal; and based on the synchronization reference signal, invoking a modulation drive strategy to generate control pulses, driving the grid-connected power conversion system to operate, and suppressing power oscillations.

[0007] As a preferred embodiment of the method for improving the stability of a grid-connected power conversion system according to the present invention, the step of decoupling the interface operating parameters by combining the real-time feedback synchronization reference signal and analyzing the state decoupling components characterizing the dynamic characteristics of the grid-connected power conversion system includes: constructing a multiphase static time domain space, mapping the collected interface operating parameters to a time-varying state vector in the multiphase static time domain space to characterize the instantaneous electrical fluctuations at the system port; locking the synchronization reference signal as the phase anchor point of the rotating coordinate transformation operator, and establishing an orthogonal projection reference system that rotates synchronously with the fundamental frequency of the grid; calculating the vector rotation projection, mapping the time-varying state vector from the multiphase static time domain space to the orthogonal projection reference system according to the phase anchor point, extracting steady-state DC quantization features, and defining them as direct-axis decoupling components and quadrature-axis decoupling components, respectively, as the state decoupling components.

[0008] The beneficial effects of this preferred technical solution are as follows: It constructs a mapping mechanism from a multiphase static time-domain space to an orthogonal projection reference system, achieving precise decoupling of the complex electrical characteristics of the system ports. By locking the synchronization reference signal as the phase anchor point, a rotating coordinate system synchronized in real time with the fundamental frequency of the power grid is established, transforming the time-varying AC state vector into steady-state direct-axis and quadrature-axis direct currents. This eliminates the phase lag and tracking error caused by direct control of AC signals, simplifying the complex coupled system into an independent control channel.

[0009] As a preferred embodiment of the method for improving the stability of a grid-connected power conversion system according to the present invention, the dynamic calculation to obtain the dynamic power compensation value includes: defining the dynamic power compensation value as a dual-channel adjustment variable containing a virtual active power compensation component and a virtual reactive power compensation component; constructing a main axis magnetic energy variation logic, extracting the autocorrelation quadratic term of the direct axis decoupling component, differentially calculating the autocorrelation quadratic term to characterize the direct axis magnetic energy storage rate, and constructing a rotating cross-axis coupling term in combination with the grid angular frequency, calculating the evolution of the difference between the direct axis magnetic energy storage rate and the rotating cross-axis coupling term, and assigning it to the virtual active power compensation component; constructing an interactive magnetic energy variation logic, extracting the cross-correlation product term of the direct axis decoupling component and the quadrature axis decoupling component, differentially calculating the cross-correlation product term to characterize the interleaved magnetic energy exchange rate, and constructing a rotating quadrature axis power term in combination with the grid angular frequency, weighting and combining the interleaved magnetic energy exchange rate and the rotating quadrature axis power term according to the energy orthogonality constraint rule, and assigning it to the virtual reactive power compensation component.

[0010] The beneficial effects of this preferred technical solution are as follows: It constructs a dynamic power calculation model based on magnetic energy variation logic, simulating the inertial response characteristics of a synchronous generator from a physical mechanism perspective. By decoupling the autocorrelation quadratic term and cross-correlation product term of the components through differential calculation, the energy storage rate and interleaved magnetic energy exchange rate of the virtual magnetic field within the system are quantified in real time, generating a dual-channel compensation variable containing virtual inertia information. This endows the converter with the ability to simulate the release and absorption of rotor kinetic energy, and can actively output damping power to counteract the rate of frequency change when the power grid is disturbed.

[0011] As a preferred embodiment of the method for improving the stability of a grid-connected power conversion system according to the present invention, the operation response characteristic reconstruction model, which maps the dynamic power compensation value to an adaptive damping term injected into the tracking loop of the operation reference command, includes: constructing an active power frequency synchronization loop, calculating the difference between the active power reference in the operation reference command and the actual active power feedback to obtain the active power tracking error, introducing the virtual active power compensation component to correct the active power tracking error, driving the frequency regulator to output a dynamic frequency adjustment amount, generating an angular frequency in combination with the rated angular frequency reference, and integrally evolving to obtain the synchronization phase angle in the synchronization reference signal; constructing a reactive power voltage stiffness loop, calculating the difference between the reactive power reference in the operation reference command and the actual reactive power feedback to obtain the reactive power tracking error, introducing the virtual reactive power compensation component to correct the reactive power tracking error, driving the voltage regulator to output a dynamic voltage adjustment amount, generating a direct-axis voltage reference in combination with the base voltage setpoint, and clamping the quadrature-axis voltage reference to a zero state.

[0012] The beneficial effects of this preferred technical solution are as follows: by mapping the dynamic power compensation value to an adaptive damping term and injecting it into the control loop, the closed-loop operation response characteristics of the converter are reconstructed. Compensation components are introduced into the active frequency and reactive voltage loops to correct tracking errors, driving the frequency and voltage regulators to adjust the output reference in real time according to the actual operating conditions of the power grid. This breaks through the limitation of rigid reference values ​​in traditional control strategies, enabling the system to actively sense and resist transient fluctuations in voltage and frequency.

[0013] As a preferred embodiment of the method for improving the stability of a grid-connected power conversion system according to the present invention, the step of calling the modulation drive strategy to generate control pulses and drive the grid-connected power conversion system includes: constructing a cascaded electromagnetic state tracking architecture; using the direct-axis voltage reference and the quadrature-axis voltage reference clamped to zero as target commands; sequentially inputting the voltage regulation outer loop and the current regulation inner loop; combining the state decoupling component as feedback data to correct multi-level electromagnetic state deviations; and outputting a modulation command vector; using the synchronization phase angle in the synchronization reference signal to perform an inverse coordinate transformation on the modulation command vector, mapping it to a stationary coordinate system to obtain a voltage space vector; and generating the control pulses through the space vector sector synthesis logic in the modulation drive strategy to drive the power semiconductor devices of the grid-connected power conversion system to operate.

[0014] As a preferred embodiment of the method for improving the stability of a grid-connected power conversion system according to the present invention, the differential calculation of the autocorrelation quadratic term includes: constructing a frequency domain noise suppression model, connecting a first-order inertial filter in series in the differential calculation path, configuring a cutoff frequency to form a low-pass signal transmission channel; inputting the autocorrelation quadratic term into the low-pass signal transmission channel, attenuating spectral components exceeding the cutoff frequency, and outputting frequency-domain constrained differential evolution characteristic values.

[0015] As a preferred embodiment of the method for improving the stability of a grid-connected power conversion system according to the present invention, the configuration of virtual energy shaping parameters includes: obtaining the physical filter inductance parameters of the grid-connected power conversion system on the AC side; establishing a virtual-physical parameter mapping mechanism, and converting the physical filter inductance parameters into virtual energy shaping parameters according to a preset ratio coefficient, so as to balance the inertia support capability and dynamic response speed of the grid-connected power conversion system.

[0016] To address the aforementioned technical problems, this invention also provides the following technical solution: a system for improving the stability of a grid-connected power conversion system, comprising: a state analysis module, used to acquire the operating reference command and interface operating parameters of the grid-connected power conversion system, and decouple the interface operating parameters by combining real-time feedback synchronization reference signals, and analyze to obtain state decoupling components characterizing the dynamic features of the grid-connected power conversion system; a transient energy compensation module, configured with a transient energy compensation model, used to introduce virtual energy shaping parameters to weight the direct-axis differential fluctuation and orthogonal-axis coupling correlation of the state decoupling components, simulate the transient energy throughput mechanism under grid impedance disturbances to quantify losses, and dynamically calculate dynamic power compensation values; a response characteristic reconstruction module, configured with a response characteristic reconstruction model, used to map the dynamic power compensation values ​​into an adaptive damping term injected into the tracking loop of the operating reference command, correct the power tracking deviation to reshape the equivalent inertia support and voltage dynamic stiffness of the grid-connected power conversion system, and update the synchronization reference signal; and a modulation drive execution module, used to generate control pulses based on the synchronization reference signal by calling a modulation drive strategy, drive the grid-connected power conversion system to operate, and suppress power oscillations.

[0017] The present invention provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the method for improving the stability of a grid-connected power conversion system.

[0018] The present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the method for improving the stability of a grid-connected power conversion system.

[0019] The beneficial effects of this invention are as follows: This invention constructs a transient energy compensation and response characteristic reconstruction model, introduces virtual energy shaping parameters to quantify and compensate for energy losses caused by grid impedance fluctuations in real time; without increasing hardware costs, it adaptively reshapes the system's equivalent inertia and voltage stiffness, effectively suppresses power oscillations, significantly improves the system's robustness under weak grid and parameter perturbation conditions, and balances steady-state accuracy and dynamic response speed. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 is a flowchart of a method for improving the stability of a grid-connected power conversion system.

[0022] Figure 2 is a structural diagram and main control block diagram of a system for improving the stability of a grid-connected power conversion system.

[0023] Figure 3 shows the system frequency diagram before and after adopting the method to improve the stability of the grid-connected power conversion system.

[0024] Figure 4 shows the ROCOF waveforms before and after the adoption of methods to improve the stability of the grid-connected power conversion system. Detailed Implementation

[0025] To make the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0026] Example 1, referring to Figures 1, 3, and 4, is an embodiment of the present invention, providing a method for improving the stability of a grid-connected power conversion system, comprising: S1, acquiring the operating reference command and interface operating parameters of the grid-connected power conversion system, decoupling the interface operating parameters by combining real-time feedback synchronization reference signals, and analyzing to obtain the state decoupling component characterizing the dynamic characteristics of the grid-connected power conversion system; S2, calling a transient energy compensation model, introducing virtual energy shaping parameters to weight the direct-axis differential fluctuation and orthogonal-axis coupling correlation of the state decoupling component, simulating the transient energy throughput mechanism under grid impedance disturbances to quantify losses, and dynamically calculating the dynamic power compensation value; S3, running a response characteristic reconstruction model, mapping the dynamic power compensation value as an adaptive damping term and injecting it into the tracking loop of the operating reference command, correcting the power tracking deviation to reshape the equivalent inertia support and voltage dynamic stiffness of the grid-connected power conversion system, and updating the synchronization reference signal; S4, based on the synchronization reference signal, calling a modulation drive strategy to generate control pulses, driving the grid-connected power conversion system to operate, and suppressing power oscillations.

[0027] It should be noted that existing virtual synchronous generator technologies typically employ fixed moments of inertia and damping coefficients, or rely on ideal grid models to design additional control strategies. When grid topology changes lead to significant impedance fluctuations, or when the grid operates under conditions of low short-circuit ratio and weak grids, these fixed-parameter control strategies cannot match the changes in system physical characteristics in real time, resulting in deterioration of system damping characteristics and easily triggering power oscillations or even instability. Furthermore, traditional methods often require the introduction of a large inertial time constant to obtain inertial support, limiting the dynamic tracking bandwidth of power commands and making it difficult to simultaneously address steady-state frequency support and transient fast response.

[0028] Therefore, to address the aforementioned problems, this invention constructs an adaptive control architecture based on real-time feedback through steps S1 to S4. First, a mapping mechanism from the multiphase static time-domain space to the orthogonal projected reference system is established, locking the synchronization reference signal as the phase anchor point. The time-varying interface operating parameters are decoupled into steady-state direct-axis and quadrature-axis components, extracting the instantaneous electrical fluctuation characteristics of the system ports. Second, based on the logic of principal axis magnetic energy variation and interactive magnetic energy variation, differential calculations are performed on the decoupled components to quantify the energy storage rate and interleaved magnetic energy exchange rate of the virtual magnetic field within the system, generating a dynamic power compensation value containing virtual inertia information. Subsequently, this compensation value is injected as an adaptive damping term into the active frequency and reactive voltage control loops to correct tracking errors in real time, driving the regulator to output dynamic frequency and voltage regulation amounts adapted to the current operating conditions. Finally, modulation commands are generated using the corrected reference to drive the power semiconductor devices.

[0029] This invention can proactively sense and compensate for the virtual inertia and damping required by the system through energy calculation at the physical mechanism level under conditions of time-varying grid impedance or weak grid. This mechanism not only effectively suppresses power oscillations caused by parameter mismatch and improves the robustness of low-inertia systems, but also achieves an organic unity of inertia support and rapid dynamic response, ensuring the stable operation of grid-connected power conversion systems under complex operating conditions.

[0030] To verify the effectiveness of this invention, a simulation experimental platform was built for testing.

[0031] Figure 3 shows a comparison of the system frequency response before and after adopting the control method of the present invention, and Figure 4 shows a comparison of the corresponding rate of change of frequency (RoCoF) waveforms. As can be seen from the figures, when subjected to the same grid disturbance, the frequency drop amplitude of the improved system is significantly reduced, and the peak value of the rate of change of frequency (RoCoF) is effectively suppressed, with a faster convergence speed, demonstrating the significant advantages of the present invention in improving the system's inertia support and damping characteristics.

[0032] Example 2, referring to Figures 1 and 2, is an embodiment of the present invention, which provides a method for improving the stability of a grid-connected power conversion system based on the previous embodiment.

[0033] Specifically, in step S1, the state decoupling components characterizing the dynamic features of the grid-connected power conversion system are analyzed by combining the real-time feedback synchronization reference signal with the decoupling interface operating parameters. This includes the following steps A1 to A3: A1: Constructing a multiphase static time domain space, and collecting the three-phase voltage and three-phase current at the common connection point of the grid-connected power conversion system in real time through sensors, collectively referred to as interface operating parameters. According to the spatial vector synthesis rule, the interface operating parameters in the three-phase static coordinate system are mapped to time-varying state vectors in the multiphase static time domain space. Let the collected three-phase variables be respectively... , , This time-varying state vector represents the instantaneous electrical fluctuation physical quantity of the system port as it changes over time.

[0034] A2: The synchronous reference signal is locked as the phase anchor point of the rotating coordinate transformation operator. The grid voltage signal is acquired through a phase-locked loop, and the real-time phase angle of the grid voltage vector is extracted. Based on this phase angle, an orthogonal projection reference frame is established that rotates synchronously with the fundamental frequency of the power grid. This reference frame includes a direct axis and a quadrature axis determined by the right-hand screw rule, and the rotational angular velocity of this coordinate system is... By maintaining consistency with the fundamental angular frequency of the power grid, the control variables exhibit DC characteristics under steady-state conditions.

[0035] A3: Calculate vector rotation projection based on phase anchor points. A rotational transformation matrix is ​​constructed to map the time-varying state vector from the multiphase stationary time domain to the orthogonal projected reference frame. Through the Park transformation operation, the sinusoidal time-varying term in the time-varying state vector is eliminated, and the steady-state DC quantization characteristics are extracted. The specific operational logic is shown in the following equation: In the formula, and These are the direct-axis decoupling components and quadrature-axis decoupling components obtained analytically, representing the projection components of the interface operating parameters onto the direct axis and quadrature axis of the rotating coordinate system, respectively. When the interface operating parameter is current, and These correspond to the active current component and the reactive current component, respectively; when the interface operating parameter is voltage... and These correspond to the components of the grid voltage vector in the synchronous rotating coordinate system, and are used as the basis for calculating the dynamic power compensation value in subsequent steps.

[0036] In this embodiment of the application, the dynamic power compensation value is dynamically calculated in step S2, including the following steps B1 to B3: B1: The dynamic power compensation value is defined as a dual-channel adjustment variable containing a virtual active power compensation component and a virtual reactive power compensation component. This dual-channel adjustment variable is set to simulate the energy throughput characteristics of the synchronous motor rotor during transient processes, wherein the virtual active power compensation component is denoted as... This is used to simulate the active power support generated by the release of rotor kinetic energy; the virtual reactive power compensation component is denoted as... It is used to simulate the magnetic energy exchange effect between the excitation winding and the armature winding.

[0037] B2: Construct the main shaft magnetic energy variation logic and extract the direct-axis decoupling component obtained in step S1. Calculate its autocorrelation quadratic term. The autocorrelation quadratic term is calculated by invoking the differential operator to obtain the physical quantity characterizing the direct-axis magnetic energy storage rate. Simultaneously, the grid angular frequency is read. A rotating transaxial coupling term is constructed. Based on the law of conservation of energy, the evolution of the difference between the direct-axis magnetic energy storage rate and the rotating transaxial coupling term is calculated, and this difference is assigned to the virtual active power compensation component. The mathematical expression of this process is shown in the following equation: In the formula, For virtual inertia coefficient, For virtual inductance parameters, For cross-axis decoupling components, This is a differential operator. This step, by calculating the rate of change of magnetic field energy, mathematically reconstructs the inertial power response of the synchronous machine rotor against frequency changes.

[0038] B3: Construct interactive magnetic energy variation logic and extract direct-axis decoupling components. Decoupled components with cross axis cross-correlated product terms Differential calculations of the cross-correlation product term yield a dynamic variable characterizing the alternating magnetic energy exchange rate. This is combined with the grid angular frequency. Construct a rotating quadrature-axis power term. Based on the energy orthogonality constraint rule, weighted combinations of the staggered magnetic energy exchange rate and the rotating quadrature-axis power term are used, and the calculation results are assigned to the virtual reactive power compensation component. The specific calculation logic is shown in the following formula: In the formula, This is the virtual damping coefficient. This step utilizes the coupling relationship between the direct-axis and quadrature-axis components to simulate the energy interaction process of the motor's internal magnetic field under transient disturbances, thereby introducing dynamic damping support into the reactive power channel.

[0039] In one optional implementation, the dynamic power compensation value can be calculated by constructing a frequency transient evolution model. The real-time angular frequency of the power grid is acquired and differential operations are performed to analyze the frequency change rate characteristics. Based on preset virtual moment of inertia parameters, the frequency change rate is mapped to an inertial power demand to counteract frequency drift. Simultaneously, the deviation between the power grid angular frequency and the rated angular frequency is calculated, and a damping power component is generated by combining it with a virtual damping coefficient. The inertial power demand and the damping power component are linearly superimposed to synthesize a virtual active power compensation component; a virtual reactive power compensation component is synthesized by multiplying the voltage amplitude deviation by the reactive power droop coefficient.

[0040] In another alternative implementation, the dynamic power compensation value can be obtained by constructing a DC-side energy storage state mapping logic calculation. The DC bus voltage of the grid-connected power conversion system is detected, and the square term of the DC bus voltage is calculated to characterize the DC-side electrostatic field energy storage state. The differential evolution of this square term is calculated to obtain the DC energy release rate. An equivalent conversion relationship between DC-side energy fluctuations and AC-side power support is established, and the DC energy release rate is converted into a virtual active power compensation component according to the energy conservation principle; simultaneously, AC port voltage fluctuations are monitored, and the reactive power increment required to maintain voltage stiffness is calculated based on the voltage sensitivity matrix and assigned to the virtual reactive power compensation component.

[0041] In this embodiment of the application, the reconstructing of the operating response characteristics to generate a control reference in step S3 includes the following steps C1 to C3: C1: Constructing the feedforward correction path of the active power frequency synchronization loop. First, read the active power reference command issued by the host computer. And obtain the actual active power feedback value of the system output from the sampling module. The difference between the two is calculated to obtain the original active power tracking error. At this point, the virtual active power compensation component calculated in step S2 is introduced. This is then subtracted from the original active power tracking error as a feedforward damping term, thereby correcting the error signal entering the regulator. This process aims to directly map the power support provided by the virtual inertia to the error processing stage, enabling the system to sense and respond to the rate of frequency change.

[0042] In this embodiment, C2 generates the synchronization phase angle. The corrected active power error signal is input to a frequency regulator, which typically employs droop control or proportional-integral control algorithms to output a dynamic frequency adjustment. The dynamic frequency adjustment amount is compared with the rated angular frequency reference of the power grid. Superimpose and synthesize the instantaneous angular frequency command of the grid-connected power conversion system. Integrating the instantaneous angular frequency command, the synchronization phase angle in the synchronization reference signal is obtained. This phase angle is not only used for subsequent coordinate transformations, but also determines the phase of the converter output voltage vector, mathematically expressed as follows: In the formula, This is the active power loop adjustment coefficient.

[0043] In one alternative implementation, the synchronization phase angle can be generated by constructing a second-order virtual rotor motion equation. A second-order differential equation incorporating the virtual moment of inertia and damping coefficient is established, with the active power tracking error and virtual active power compensation component used as mechanical power inputs, and the actual grid load used as the electromagnetic power output. Solving this differential equation yields the angular velocity deviation of the virtual rotor, and then integrating the angular velocity deviation to obtain the rotor position angle, which is defined as the synchronization phase angle in the synchronization reference signal.

[0044] In another alternative implementation, the synchronization phase angle can be generated using a phase superposition mechanism based on a phase-locked loop (PLL). The PLL tracks the phase of the fundamental positive-sequence component of the grid voltage in real time and uses it as the grid synchronization angle. The dynamic frequency regulation output from the frequency regulator is input to an integrator to obtain the load angle deviation. The grid synchronization angle and the load angle deviation are algebraically summed to synthesize the final synchronization phase angle used for coordinate transformation, thereby achieving flexible synchronization between the converter output voltage vector and the grid voltage vector.

[0045] C3: Construct a reactive power voltage stiffness loop and generate a voltage reference. Calculate the reactive power reference command. Compared with actual reactive power feedback value The difference. Similarly, a virtual reactive power compensation component is introduced. The difference is corrected, and the corrected signal is input into the voltage regulator to calculate the dynamic voltage regulation. The adjustment amount is compared with the base voltage setpoint. Summation generates a direct-axis voltage reference. Simultaneously, following the voltage-oriented vector control principle, the quadrature-axis voltage reference is... The forced clamp is set to a zero state to ensure decoupling control of reactive power and voltage amplitude. The logic for generating the voltage reference is shown in the following equation: In the formula, This represents the reactive power loop regulation coefficient. Through the above steps, the system transforms the virtual energy calculation results into specific voltage and phase control commands, completing the mapping from the energy layer to the control layer.

[0046] In an optional implementation, operational response characteristics can be reconstructed by constructing a dynamic correction architecture for reference commands. The virtual active power compensation component and virtual reactive power compensation component in the dynamic power compensation value are directly superimposed onto the original active power reference and reactive power reference issued by the host computer, respectively, to synthesize a target command trajectory with dynamic inertial characteristics. The deviation between this target command trajectory and the actual system feedback value is input to the regulator, forcing the control loop to track the dynamic target containing virtual inertia information, thereby driving the frequency regulator and voltage regulator to output corrected angular frequency and direct-axis voltage references.

[0047] In another alternative implementation, operational response characteristic reconstruction can be achieved by constructing an output port feedforward modulation mechanism. Maintaining the original closed-loop structure of the active power frequency and reactive power voltage regulation loops, the dynamic power compensation value is converted into equivalent frequency and voltage amplitude biases using a preset inverse droop coefficient. These two biases are directly superimposed onto the output ports of the frequency and voltage regulators, bypassing the time delay of the internal integral stage of the regulators, and directly modulating the final output synchronization reference signal frequency and direct-axis voltage reference, thus achieving a rapid feedforward response to grid disturbances.

[0048] Specifically, in step S4, the modulation drive strategy is invoked to generate control pulses to drive the grid-connected power conversion system, including the following steps D1 to D3: D1: Constructing a cascaded electromagnetic state tracking architecture. The direct-axis voltage reference generated in step S3 is used... Cross-axis voltage reference with clamped to zero state As target commands, these commands are sequentially input into the voltage regulation outer loop and current regulation inner loop of the control system. During this closed-loop control process, the direct-axis and quadrature-axis decoupling components (such as the inductor current feedback value) obtained from step S1 are introduced as state feedback data to correct multi-level electromagnetic state deviations in real time. The current inner loop regulator calculates and outputs a modulation command vector in a synchronously rotating coordinate system based on the deviation between the voltage outer loop output and the actual current, denoted as... and .

[0049] D2: Utilize the synchronization phase angle in the synchronization reference signal generated in step S3 Inverse transformation of the modulation command vector. Construct an inverse rotation transformation matrix to transform the modulation command components in the rotating coordinate system. and Mapping back to the stationary coordinate system yields the voltage space vector in the two-phase stationary coordinate system. and This transformation converts the control signal from the mathematical model domain to the physical execution domain. The specific mathematical operations are as follows: In this embodiment, D3: executes space vector sector synthesis logic (SVPWM). Based on voltage space vector... and The amplitude and phase information are used to determine the sector position of the reference voltage vector in the space vector hexagon. Based on the volt-second balance principle, the duration of action of two adjacent fundamental non-zero voltage vectors and the zero vector is calculated. A PWM control pulse signal with a corresponding duty cycle is generated based on the calculated time parameters. This signal is applied to the power semiconductor devices (such as IGBTs or SiC MOSFETs) in the main circuit of the grid-connected power conversion system through a gate drive circuit, controlling their on / off states. This synthesizes a three-phase AC voltage with controllable frequency and amplitude at the output port, driving the system to operate stably.

[0050] In an alternative implementation, control pulses can be generated using a sinusoidal pulse width modulation (SPWM) strategy. The voltage space vector in a two-phase stationary coordinate system is converted into a modulated wave signal in a three-phase stationary coordinate system. A high-frequency triangular carrier signal is constructed, and the three-phase modulated wave signal is input to a comparator along with this triangular carrier signal. Based on the comparison logic, high and low level states are output to generate a control pulse sequence that drives the power semiconductor device to turn on and off.

[0051] In another alternative implementation, control pulses can be generated using a discontinuous pulse width modulation (DPWM) strategy. During the execution of the space vector sector synthesis logic, a zero-sequence component injection algorithm is introduced, clamping the three-phase modulated wave to the positive or negative terminal of the DC bus within a specific interval of each fundamental cycle. Switching of the corresponding phase power devices is stopped within the clamped interval, and PWM waveforms are generated only in the non-clamped intervals. This method reduces the average switching frequency and switching losses of the power semiconductor devices while maintaining equivalent line voltage waveforms.

[0052] Example 3 illustrates a method for improving the stability of a grid-connected power conversion system. It should be noted that the technical solution of this system for improving the stability of a grid-connected power conversion system is based on the same concept as the method for improving the stability of a grid-connected power conversion system described above. Details not described in detail in the technical solution of the system for improving the stability of a grid-connected power conversion system in this example can be found in the description of the technical solution of the method for improving the stability of a grid-connected power conversion system described above.

[0053] Referring to Figure 2, this embodiment also provides a system for improving the stability of a grid-connected power conversion system, including: a state decoupling analysis module, used to construct a mapping from multiphase static time-domain space to an orthogonal projection reference system by combining real-time feedback synchronous reference signal decoupling interface operating parameters, calculate vector rotation projection, extract steady-state DC quantization features, and output direct-axis decoupling components and quadrature-axis decoupling components; a dynamic compensation calculation module, used to construct the main axis magnetic energy variation logic and interactive magnetic energy variation logic, differentially calculate the autocorrelation quadratic term and cross-correlation product term of the direct-axis decoupling components, calculate the direct-axis magnetic energy storage rate and interleaved magnetic energy exchange rate by combining the grid angular frequency, and generate dynamic power compensation values ​​including virtual active power compensation components and virtual reactive power compensation components; and an operating characteristic reconstruction module. The system is used to construct active frequency synchronization loops and reactive voltage stiffness loops, mapping dynamic power compensation values ​​to adaptive damping terms injected into the tracking loop of the operating reference command, correcting active and reactive tracking errors, and driving the regulator to output dynamic frequency adjustment and direct-axis voltage reference. The modulation drive control module is used to construct a cascaded electromagnetic state tracking architecture, inputting the direct-axis voltage reference into the voltage and current adjustment loops, combining state decoupling components to correct electromagnetic state deviations, outputting modulation command vectors, and performing inverse coordinate transformation and spatial vector sector synthesis to generate control pulses. The parameter configuration and filtering module is used to establish a virtual and physical parameter mapping mechanism, configure virtual energy shaping parameters, and construct a frequency domain noise suppression model and a first-order inertial filter differential operation path.

[0054] This embodiment also provides an electronic device applicable to a method for improving the stability of a grid-connected power conversion system, comprising: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement the method for improving the stability of a grid-connected power conversion system as proposed in the above embodiment.

[0055] This embodiment also provides a storage medium storing a computer program that, when executed by a processor, implements a method for improving the stability of a grid-connected power conversion system as proposed in the above embodiments.

[0056] The storage medium proposed in this embodiment and the method for improving the stability of a grid-connected power conversion system proposed in the above embodiments belong to the same inventive concept. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.

[0057] Based on the above description of the implementation methods, those skilled in the art can clearly understand that the present invention can be implemented using software and necessary general-purpose hardware, and of course, it can also be implemented using hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk, or optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of the various embodiments of the present invention.

[0058] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for improving the stability of a grid-connected power conversion system, characterized in that: This includes acquiring the operating reference commands and interface operating parameters of the grid-connected power conversion system, decoupling the interface operating parameters by combining the real-time feedback synchronization reference signal, and analyzing the state decoupling components that characterize the dynamic features of the grid-connected power conversion system. The transient energy compensation model is invoked, and virtual energy shaping parameters are introduced to weight the direct-axis differential fluctuations and orthogonal-axis coupling of the state decoupling components. This simulates the transient energy throughput mechanism under grid impedance disturbances to quantify losses and dynamically calculates the dynamic power compensation value. The response characteristic reconstruction model is then run, mapping the dynamic power compensation value to an adaptive damping term injected into the tracking loop of the operating reference command. This corrects the power tracking deviation to reshape the equivalent inertia support and voltage dynamic stiffness of the grid-connected power conversion system and updates the synchronization reference signal. Based on the synchronization reference signal, a modulation drive strategy is invoked to generate control pulses, which drive the grid-connected power conversion system to operate and suppress power oscillations.

2. The method for improving the stability of a grid-connected power conversion system as described in claim 1, characterized in that: The process of decoupling the interface operating parameters by combining real-time feedback with the synchronization reference signal to obtain the state decoupling components characterizing the dynamic features of the grid-connected power conversion system includes: constructing a multiphase static time domain space, mapping the collected interface operating parameters to time-varying state vectors within the multiphase static time domain space to characterize the instantaneous electrical fluctuations at the system ports; locking the synchronization reference signal as the phase anchor point of the rotating coordinate transformation operator, and establishing an orthogonal projection reference system that rotates synchronously with the grid fundamental frequency; calculating the vector rotation projection, mapping the time-varying state vectors from the multiphase static time domain space to the orthogonal projection reference system based on the phase anchor point, extracting steady-state DC quantization features, and defining them as direct-axis decoupling components and quadrature-axis decoupling components, respectively, as the state decoupling components.

3. The method for improving the stability of a grid-connected power conversion system as described in claim 2, characterized in that: The dynamic calculation to obtain the dynamic power compensation value includes: defining the dynamic power compensation value as a dual-channel adjustment variable containing a virtual active power compensation component and a virtual reactive power compensation component; constructing a main axis magnetic energy variation logic, extracting the autocorrelation quadratic term of the direct axis decoupling component, differentially calculating the autocorrelation quadratic term to characterize the direct axis magnetic energy storage rate, and constructing a rotating cross-axis coupling term in combination with the grid angular frequency, calculating the evolution of the difference between the direct axis magnetic energy storage rate and the rotating cross-axis coupling term, and assigning it to the virtual active power compensation component; constructing an interactive magnetic energy variation logic, extracting the cross-correlation product term of the direct axis decoupling component and the quadrature axis decoupling component, differentially calculating the cross-correlation product term to characterize the staggered magnetic energy exchange rate, and constructing a rotating quadrature axis power term in combination with the grid angular frequency, weighting and combining the staggered magnetic energy exchange rate and the rotating quadrature axis power term according to the energy orthogonality constraint rule, and assigning it to the virtual reactive power compensation component.

4. The method for improving the stability of a grid-connected power conversion system as described in claim 3, characterized in that: The operational response characteristic reconstruction model, which maps the dynamic power compensation value to an adaptive damping term injected into the tracking loop of the operational reference command, includes: constructing an active power frequency synchronization loop, calculating the difference between the active power reference in the operational reference command and the actual active power feedback to obtain the active power tracking error, introducing the virtual active power compensation component to correct the active power tracking error, driving the frequency regulator to output a dynamic frequency adjustment amount, generating an angular frequency in combination with the rated angular frequency reference, and integrally evolving to obtain the synchronization phase angle in the synchronization reference signal; constructing a reactive power voltage stiffness loop, calculating the difference between the reactive power reference in the operational reference command and the actual reactive power feedback to obtain the reactive power tracking error, introducing the virtual reactive power compensation component to correct the reactive power tracking error, driving the voltage regulator to output a dynamic voltage adjustment amount, generating a direct-axis voltage reference in combination with the base voltage setpoint, and clamping the quadrature-axis voltage reference to a zero state.

5. The method for improving the stability of a grid-connected power conversion system as described in claim 4, characterized in that: The step of invoking the modulation drive strategy to generate control pulses and drive the grid-connected power conversion system includes: constructing a cascaded electromagnetic state tracking architecture; using the direct-axis voltage reference and the quadrature-axis voltage reference clamped to zero as target commands; sequentially inputting the voltage regulation outer loop and the current regulation inner loop; combining the state decoupling component as feedback data to correct multi-level electromagnetic state deviations; and outputting a modulation command vector; using the synchronization phase angle in the synchronization reference signal to perform an inverse coordinate transformation on the modulation command vector, mapping it to a stationary coordinate system to obtain a voltage space vector; and generating the control pulses through the space vector sector synthesis logic in the modulation drive strategy to drive the power semiconductor devices of the grid-connected power conversion system to operate.

6. The method for improving the stability of a grid-connected power conversion system as described in claim 3, characterized in that: The differential calculation of the autocorrelation quadratic term includes: constructing a frequency domain noise suppression model, connecting a first-order inertial filter in series in the differential operation path, configuring a cutoff frequency to form a low-pass signal transmission channel; inputting the autocorrelation quadratic term into the low-pass signal transmission channel, attenuating spectral components exceeding the cutoff frequency, and outputting frequency-domain constrained differential evolution characteristic values.

7. The method for improving the stability of a grid-connected power conversion system as described in claim 2, characterized in that: The configuration of virtual energy shaping parameters includes: obtaining the physical filter inductance parameters of the grid-connected power conversion system on the AC side; establishing a virtual-physical parameter mapping mechanism, and converting the physical filter inductance parameters into virtual energy shaping parameters according to a preset ratio coefficient, so as to balance the inertia support capability and dynamic response speed of the grid-connected power conversion system.

8. A system for improving the stability of a grid-connected power conversion system, comprising the method for improving the stability of a grid-connected power conversion system as described in any one of claims 1 to 7, characterized in that, include: The state analysis module is used to obtain the operating reference command and interface operating parameters of the grid-connected power conversion system, and decouple the interface operating parameters by combining the real-time feedback synchronization reference signal, and analyze the state decoupling component that characterizes the dynamic characteristics of the grid-connected power conversion system. The transient energy compensation module is equipped with a transient energy compensation model, which introduces virtual energy shaping parameters to weight the direct-axis differential fluctuations and orthogonal-axis coupling of the state decoupling components, simulates the transient energy throughput mechanism under grid impedance disturbances to quantify losses, and dynamically calculates the dynamic power compensation value; the response characteristic reconstruction module is equipped with a response characteristic reconstruction model, which maps the dynamic power compensation value into an adaptive damping term injected into the tracking loop of the operating reference command, corrects the power tracking deviation to reshape the equivalent inertia support and voltage dynamic stiffness of the grid-connected power conversion system, and updates the synchronization reference signal; The modulation drive execution module is used to generate control pulses based on the synchronization reference signal by calling the modulation drive strategy, thereby driving the grid-connected power conversion system to operate and suppressing power oscillations.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method for improving the stability of a grid-connected power conversion system according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of any one of claims 1 to 7 of the method for improving the stability of a grid-connected power conversion system.

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