A synchronous control and modeling method for grid-type converters

Abstract

This invention discloses a synchronous control and modeling method for grid-connected converters, including constructing a grid-connected converter topology, designing a multi-mode synchronous control strategy for synchronous generator control, employing a virtual synchronous generator mode when the grid short-circuit ratio is greater than a first threshold and there are no faults; employing fixed-frequency control when the voltage drop is greater than a second threshold; and initiating inertial synchronous control when the frequency deviation is greater than a third threshold. For current limiting control, CLC limiting and PSL / PLL synchronous source coordinated protection are implemented. Based on the converter voltage and current dynamic equations, d-axis and q-axis current reference values ​​are obtained, and different limiting strategies are adopted for different scenarios. An average value model is established using the principle of fundamental frequency dynamic retention and ignoring switching details. Specialized control strategies are designed for photovoltaic, wind turbine, and energy storage systems respectively to achieve coordinated control effects. This invention is applicable to new energy grid connection, DC transmission, and reactive power compensation scenarios, providing support for the stable operation of high-voltage and high-efficiency power systems.

Description

Technical Field

[0001] This invention belongs to the field of power system automation and new energy grid connection technology, specifically to a synchronous control and modeling method for grid-type converters. Background Technology

[0002] Currently, the power system is accelerating its transformation towards a high proportion of new energy sources and a high proportion of power electronic equipment. During this transformation, the characteristics of the traditional power grid, which is dominated by synchronous generators, have undergone fundamental changes. On the one hand, new energy units and power electronic equipment generally adopt a control mode that decouples the prime mover input power from the grid-side electromagnetic power, lacking the inherent spinning reserve capacity and rotational inertia of synchronous generators. The inertial time constant of a 1000MW thermal power unit can reach 8~10s, while the equivalent inertia of variable speed wind turbines and photovoltaic units is close to zero, resulting in a significant reduction in the overall inertia of the system, weakened frequency regulation capability, and a significant increase in the risk of exceeding frequency deviation standards. On the other hand, the intermittency and volatility of new energy power generation and the rapid response characteristics of power electronic equipment place higher demands on the voltage support and reactive power balance capabilities of the power grid. The traditional power grid stability control system is no longer suitable for the operational needs of the new power system.

[0003] Most power electronic converters widely used in current power systems employ grid-following control strategies, relying on phase-locked loops (PLLs) to track the voltage phase and frequency at the grid connection point in real time to achieve synchronization with the grid. However, this control method presents significant stability risks in weak grid scenarios—when grid strength decreases, the dynamic response of the PLL is prone to resonance with the grid impedance, leading to converter loss of synchronization and even grid voltage collapse. To address this issue, grid-connected converters have become a research hotspot. Existing grid-connected control strategies, such as power droop control and virtual synchronous machine control, while simulating the external characteristics of synchronous generators, still have significant limitations: power droop control lacks inertial support, easily causing grid voltage and frequency oscillations; virtual synchronous machine control, although introducing virtual inertia, suffers from insufficient power angle stability in weak grids, making it difficult to cover multiple operating conditions such as normal operation, grid disturbances, and faults; a single control strategy cannot adapt to different grid strengths and energy types, exhibiting poor control adaptability and failing to meet the stable operation requirements in complex scenarios.

[0004] In addition, existing grid-type converter technology faces two major bottlenecks: First, it has weak fault ride-through capability. When a fault occurs (such as a three-phase short circuit or voltage drop), the converter output current is prone to overshoot, which may damage power electronic devices. Moreover, the switching delay between the synchronization source (such as the power synchronization loop) and the phase-locked loop is large (usually >100ms), which can easily lead to commutation failure and fault recovery time exceeding 500ms. Second, the simulation efficiency is low. Although the traditional IGBT switching stage can accurately describe the device dynamics, the simulation time in large-scale systems is too long—the electromagnetic transient simulation time for a system of 100 direct-drive wind turbines can reach more than 120 minutes, which cannot support rapid analysis and optimization design. At the same time, existing average value models are mostly limited to two-level topologies, do not cover modular multilevel converters, and have dynamic errors exceeding 10%, making it difficult to balance efficiency and accuracy. In addition, due to the slow response of photovoltaic active power reserve (>200ms), insufficient wind turbine inertia transfer, and poor energy storage effect in smoothing fluctuations (DC bus fluctuation >8%), existing technologies are no longer able to support the safe and stable operation of "high-voltage" power systems. There is an urgent need for a grid-type converter control and modeling technology with multi-scenario adaptability, rapid fault ride-through, efficient simulation, and multi-energy coordination capabilities. Summary of the Invention

[0005] The technical problem to be solved by this invention is to address the issues of poor control adaptability, difficulty in fault ride-through, low simulation efficiency, and weak energy adaptability of grid-type converters in power systems. This invention provides a synchronous control and modeling method for grid-type converters, achieving optimal control under different grid strengths and operating conditions, and significantly improving the system's fault ride-through capability.

[0006] To solve the above technical problems, the present invention adopts the following technical solution:

[0007] A synchronous control and modeling method for a grid-type converter includes the following steps:

[0008] S1. Construct a grid-type converter topology, which includes a front-end energy unit, a VSC (Voltage Source Converter) unit, a DC energy storage unit, and an AC filter unit;

[0009] S2. Based on the grid-type converter topology, a multi-mode synchronous control strategy is designed for the control of the synchronous generator. When the grid short-circuit ratio is greater than the first threshold and there is no fault, the virtual synchronous generator mode is adopted; when the voltage drop is greater than the second threshold, fixed-frequency control is adopted; when the frequency deviation is greater than the third threshold, inertial synchronous control is activated.

[0010] S3. Implement CLC (Current Limiting Control) limiting and PSL (Power Synchronization Loop) / PLL (Phase-Locked Loop) synchronization source coordinated protection in current limiting control. Based on the converter voltage and current dynamic equation, obtain the d-axis and q-axis current reference values, and then obtain the current reference value magnitude. Different limiting strategies are adopted for different scenarios.

[0011] S4. Adopting the principle of fundamental frequency dynamic preservation and switching detail ignoring, establish an average value model that adapts to multiple topologies of two-level VSC and MMC (Modular Multilevel Converter);

[0012] S5. Design specific control strategies for photovoltaic, wind turbine, and energy storage systems to achieve synergistic control effects.

[0013] Furthermore, in step S1, the front-end energy unit includes an adaptive energy storage unit with a rated power of 1MW and a rated voltage of 0.5kV, a photovoltaic array with a maximum power of 1.02MW and an open-circuit voltage of 1.24kV, a direct-drive wind turbine with a rated power of 2MW and a generator voltage of 0.69kV, and a doubly-fed wind turbine with a rated power of 2MW and an outlet bus voltage of 33kV.

[0014] The VSC unit includes a two-level topology with 6 IGBT modules and an MMC topology with 152 sub-modules; the switching frequency of the IGBT modules is 4950Hz, and the capacitance of the sub-modules is 2800μF and the bridge arm inductance is 50mH.

[0015] The DC energy storage unit includes a bidirectional DC / DC converter and a smoothing capacitor; the bidirectional DC / DC converter is in Buck-Boost mode, with an inductor of 250μF and a capacitor of 10mF; the two-level topology of the smoothing capacitor is 2mF, and the MMC topology is 1.28mF.

[0016] The AC filtering unit includes an LCL filter; the total inductance of the LCL filter is 0.269mH, the filter capacitor is 115.85μF, and the damping resistor is 0.508Ω; among which, the first inductor L1=0.1345mH and the second inductor L2=0.1345mH.

[0017] Furthermore, in step S2, in the virtual synchronous generator mode, a virtual inertia J = 8.43 kg·m², a damping coefficient D = 0.05, and a primary frequency regulation coefficient k are introduced. f =50, used to provide inertial support during normal operation;

[0018] In fixed-frequency control, a fixed 50Hz frequency signal is output as the frequency reference source for the local power grid and is applied in fault emergency scenarios.

[0019] In inertial synchronous control, the angular frequency of the grid-side converter is linked to the DC voltage. In a wind turbine system, when the wind energy captured by the turbine increases (i.e., the DC voltage rises), the angular frequency of the grid-side converter is synchronously increased; conversely, when the wind energy captured by the turbine decreases (i.e., the DC voltage decreases), the angular frequency of the grid-side converter is synchronously decreased. The real-time rotational speed signal of the turbine is acquired, filtered for noise by a low-pass filter, and then multiplied by an adjustment coefficient K. c The inertia-transmitted power compensation is obtained and superimposed on the active power reference value of the grid-side converter. Based on the angular frequency obtained by linkage, the phase angle command of the grid-side converter output voltage is calculated by integration. Combined with the active power reference value after superimposed inertia compensation, the voltage amplitude command is determined. The phase angle command and the voltage amplitude command are input together into the PWM modulation module to control the switching action of the grid-side converter, adjust the output power and voltage phase of the AC side, and at the same time use the wind turbine inertia to buffer power fluctuations.

[0020] Furthermore, in step S3, the CLC limiting and PSL / PLL synchronous source coordinated protection is based on the converter voltage and current dynamic equations as follows:

[0021] ;

[0022] ;

[0023] in, This refers to the inductance value of the filter inductor on the output side of the converter. , These represent the d-axis and q-axis components of the converter output current, respectively. , These represent the d-axis and q-axis components of the converter bridge arm output voltage, respectively. , These represent the d-axis and q-axis components of the grid connection point voltage, respectively. This is the equivalent resistance of the filter inductor on the output side of the converter. Angular frequency;

[0024] When the current reference value magnitude When the current exceeds the preset maximum value, CLC limiting is activated; where, , , These are the reference values ​​for the d-axis and q-axis currents, respectively.

[0025] In wind turbine scenarios, d-axis priority limiting is used, i.e. , ; STATCOM scenarios use q-axis priority limiting; general scenarios use proportional limiting;

[0026] After limiting, corresponding fault signals are obtained based on different scenarios. When the fault signal is 1, the synchronization source is switched from PSL to PLL. When the fault signal is 0 and stable for 0.1s, it is switched back to PSL.

[0027] Furthermore, in step S4, for the two-level VSC scenario, the average value model is established, including: using a controlled voltage source on the AC side. Equivalent, of which The modulation ratio, This is the DC bus voltage. The fundamental initial phase angle of the AC side output voltage of the converter; the DC side uses a controlled current source. Equivalent to the equivalent capacitance, where To measure the output power in AC mode, the equivalent capacitance on the DC side is set to 2mF.

[0028] For MMC scenarios, the average value model is established including: a controlled voltage source on the AC side. Equivalent This refers to the number of submodules in a single bridge arm of the MMC. The voltage of the submodule capacitor is 1.28mF. The DC side is equivalent to a controlled current source and an equivalent capacitor.

[0029] Furthermore, in step S5, in the photovoltaic system, the maximum power point voltage V of the photovoltaic cell is used. mpp Right-side active power reserve control, reserve power for Target voltage for ,in Maximum power; the Boost converter is adjusted by a PI controller, and the standby release response time is ≤0.1s; MPPT (Maximum Power Point Tracking) is achieved using the perturbation-observation method, and ≥0.04pu of active power is generated when the frequency drops by 0.1Hz;

[0030] In the wind turbine system, the active power reference value of the direct-drive wind turbine is superimposed on the turbine side and connected in series with a 0.1s low-pass filter, which increases the equivalent inertial time constant to 0.3s; the doubly-fed wind turbine generates reactive power through the rotor-side converter, with a response time ≤0.05s.

[0031] In the energy storage system, a dual closed-loop control system with an outer voltage loop and an inner current loop is adopted, and the PI parameter K of the outer voltage loop is... p =5、K i =0.05, current inner loop PI parameter K p =2、K i =0.1, DC bus fluctuation ≤5%.

[0032] Furthermore, the present invention also proposes an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the synchronous control and modeling method for the grid-type converter.

[0033] Furthermore, the present invention also proposes a computer-readable storage medium storing a computer program, which, when executed by a processor, performs the synchronous control and modeling method for the grid-type converter.

[0034] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects:

[0035] 1. This invention constructs a four-layer universal topology architecture consisting of a front-end energy unit, a VSC conversion unit, a DC energy storage unit, and an AC filter unit. It possesses broad scenario adaptability and can seamlessly integrate with diverse application scenarios such as energy storage systems, photovoltaic arrays, direct-drive / doubly-fed wind turbine generators, and dual-terminal flexible DC transmission systems. The VSC conversion unit encompasses two-level and modular multi-level topologies. Through a unified control strategy and reuse design, it avoids topology reconfiguration in single scenarios, significantly reducing design and operation costs in engineering applications. It provides an integrated solution for diverse power system scenarios such as high-proportion renewable energy grid connection, DC transmission, and reactive power compensation.

[0036] 2. This invention proposes a multi-mode adaptive synchronous control strategy, which integrates five control modes: fixed-frequency control, power droop control, power synchronization control, virtual synchronous generator control, and inertial synchronization control. It achieves dynamic switching based on key operating parameters such as grid short-circuit ratio and frequency deviation, breaking through the adaptation limitations of traditional single control modes and realizing optimal control under different grid strengths and operating conditions.

[0037] 3. This invention designs a capacitor-inductor-capacitor limiting technology and a synchronous source collaborative protection mechanism. Based on the converter voltage and current dynamic equation, it accurately controls the fault current amplitude to not exceed 1.1 per unit value, reduces the commutation failure rate to zero, significantly improves the system's fault ride-through capability, and solves the technical problems of severe fault current overshoot, lag in dynamic response, and high commutation failure rate in the prior art.

[0038] 4. This invention establishes an average value modeling method for multi-topology adaptation. Based on the modeling principle of fundamental frequency dynamic preservation and switching detail ignoring, equivalent models are constructed for two-level VSC and MMC topologies respectively. This model improves the simulation efficiency by 5 to 10 times compared with the traditional IGBT switching stage. In a large-scale system composed of 100 direct-drive wind turbines, the simulation time is reduced from 120 minutes to 15 minutes, and the error of key dynamic indicators such as frequency response and fault current peak does not exceed 5%, providing an efficient and reliable simulation tool for system design and optimization. Attached Figure Description

[0039] Figure 1 This is a flowchart illustrating the overall implementation of the present invention.

[0040] Figure 2 This is a diagram showing the AC bus voltage results of the grid-type photovoltaic model of the present invention.

[0041] Figure 3 This is a graph showing the test results of the short-circuit current support capability of the present invention.

[0042] Figure 4 The graph shows the inertial response and primary frequency modulation test results of this invention.

[0043] Figure 5 This is a graph showing the test results of the short-circuit current support capability of the present invention.

[0044] Figure 6 This is a diagram showing the grid connection fault response results of the direct-drive wind turbine of the present invention.

[0045] Figure 7 This is a waveform diagram of the active power during startup of the present invention.

[0046] Figure 8 This is a waveform diagram of active power during a short-circuit fault according to the present invention.

[0047] Figure 9 This is a waveform diagram of the active power of the energy unloading device of the present invention.

[0048] Figure 10 This is a diagram showing the grid connection fault response results of the doubly fed wind turbine of the present invention.

[0049] Figure 11 This is a waveform diagram of the DC side voltage and current of the present invention. Detailed Implementation

[0050] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0051] To achieve the above objectives, this invention proposes a synchronous control and modeling method for grid-type converters, such as... Figure 1As shown, the specific steps are as follows:

[0052] S1. Construct a grid-type converter topology, which includes a front-end energy unit, a VSC (Voltage Source Converter) unit, a DC energy storage unit, and an AC filter unit; specifically:

[0053] The front-end energy unit includes an adaptive energy storage unit with a rated power of 1MW and a rated voltage of 0.5kV, a photovoltaic array with a maximum power of 1.02MW and an open-circuit voltage of 1.24kV, a direct-drive wind turbine with a rated power of 2MW and a generator voltage of 0.69kV, and a doubly-fed wind turbine with a rated power of 2MW and an outlet bus voltage of 33kV.

[0054] The VSC unit includes a two-level topology with 6 IGBT modules and an MMC topology with 152 sub-modules; the switching frequency of the IGBT modules is 4950Hz, and the capacitance of the sub-modules is 2800μF and the bridge arm inductance is 50mH.

[0055] The DC energy storage unit includes a bidirectional DC / DC converter and a smoothing capacitor; the bidirectional DC / DC converter is in Buck-Boost mode, with an inductor of 250μF and a capacitor of 10mF; the two-level topology of the smoothing capacitor is 2mF, and the MMC topology is 1.28mF.

[0056] The AC filtering unit includes an LCL filter; the total inductance of the LCL filter is 0.269mH, the filter capacitor is 115.85μF, and the damping resistor is 0.508Ω; among which, the first inductor L1=0.1345mH and the second inductor L2=0.1345mH.

[0057] S2. Based on the grid-connected converter topology, a multi-mode synchronous control strategy is designed for the synchronous generator control. When the grid short-circuit ratio is >3 and there are no faults, the virtual synchronous generator mode is adopted; when the voltage drop is >20%, fixed-frequency control is adopted; when the frequency deviation is >0.1Hz, inertial synchronous control is activated; specifically:

[0058] In the virtual synchronous generator mode, a virtual inertia J = 8.43 kg·m², a damping coefficient D = 0.05, and a primary frequency regulation coefficient k are introduced. f =50, used to provide inertial support during normal operation;

[0059] In fixed-frequency control, a fixed 50Hz frequency signal is output as the frequency reference source for the local power grid and is applied in fault emergency scenarios.

[0060] In inertial synchronous control, the angular frequency of the grid-side converter is linked to the DC voltage. In a wind turbine system, when the wind energy captured by the turbine increases (i.e., the DC voltage rises), the angular frequency of the grid-side converter is synchronously increased; conversely, when the wind energy captured by the turbine decreases (i.e., the DC voltage decreases), the angular frequency of the grid-side converter is synchronously decreased. The real-time rotational speed signal of the turbine is acquired, filtered for noise by a low-pass filter, and then multiplied by an adjustment coefficient K. c The inertia-transmitted power compensation is obtained and superimposed on the active power reference value of the grid-side converter. Based on the angular frequency obtained by linkage, the phase angle command of the output voltage of the grid-side converter is calculated by integration. Combined with the active power reference value after superimposed inertia compensation, the voltage amplitude command is determined. The phase angle command and the voltage amplitude command are input together into the PWM modulation module to control the switching action of the grid-side converter, adjust the output power and voltage phase of the AC side, maintain the grid frequency stability, and at the same time use the wind turbine inertia to buffer power fluctuations.

[0061] S3. Implement CLC (Current Limiting Control) limiting and PSL (Power Synchronization Loop) / PLL (Phase-Locked Loop) synchronization source coordinated protection in current limiting control. Based on the converter voltage and current dynamic equations, obtain the d-axis and q-axis current reference values, and then obtain the current reference value magnitude. Different limiting strategies are adopted for different scenarios; specifically:

[0062] The CLC limiting and PSL / PLL synchronous source coordinated protection is based on the converter voltage and current dynamic equations:

[0063] ;

[0064] ;

[0065] in, This refers to the inductance value of the filter inductor on the output side of the converter. , These represent the d-axis and q-axis components of the converter output current, respectively. , These represent the d-axis and q-axis components of the converter bridge arm output voltage, respectively. , These represent the d-axis and q-axis components of the grid connection point voltage, respectively. This is the equivalent resistance of the filter inductor on the output side of the converter. Angular frequency;

[0066] When the current reference value magnitude When the current exceeds the preset maximum value, CLC limiting is activated; where, , , These are the reference values ​​for the d-axis and q-axis currents, respectively.

[0067] In wind turbine scenarios, d-axis priority limiting is used, i.e. , ; STATCOM scenarios use q-axis priority limiting; general scenarios use proportional limiting;

[0068] After limiting, corresponding fault signals are obtained based on different scenarios. When the fault signal is 1 (i.e., AC voltage ≤ 0.87pu and DC voltage ≥ 1.07pu), the synchronization source is switched from PSL to PLL. When the fault signal is 0 and stabilizes for 0.1s, it is switched back to PSL.

[0069] S4. Employing the principle of fundamental frequency dynamic retention and ignoring switching details, an average value model is established to adapt to multiple topologies of two-level VSC and MMC (Modular Multilevel Converter); specifically:

[0070] For a two-level VSC scenario, the average value model is established, including: a controlled voltage source on the AC side. Equivalent, of which The modulation ratio, This is the DC bus voltage. The fundamental initial phase angle of the AC side output voltage of the converter; the DC side uses a controlled current source. Equivalent to the equivalent capacitance, where To measure the output power in AC mode, the equivalent capacitance on the DC side is set to 2mF.

[0071] For MMC scenarios, the average value model is established including: a controlled voltage source on the AC side. Equivalent This refers to the number of submodules in a single bridge arm of the MMC. , This refers to the capacitor voltage of the submodule. Take 2.8kV; the DC side is equivalent to a controlled current source and an equivalent capacitor, and the equivalent capacitor on the DC side is taken as 1.28mF.

[0072] S5. Specific control strategies are designed for photovoltaic, wind turbine, and energy storage systems respectively to achieve synergistic control effects in terms of active power reserve, inertia transfer, and fluctuation smoothing; specifically:

[0073] In a photovoltaic system, the maximum power point voltage V of the photovoltaic cell is used. mpp Right-side active power reserve control, reserve power for Target voltage for ,in For maximum power; via PI controller (K p =2、T i =0.1) Adjust the Boost converter, and the standby release response time is ≤0.1s; use the perturbation and observation method to achieve MPPT (Maximum Power Point Tracking), and generate ≥0.04pu of active power when the frequency drops by 0.1Hz;

[0074] In the wind turbine system, the active power reference value of the direct-drive wind turbine is superimposed on the turbine side, and a 0.1s low-pass filter is connected in series, increasing the equivalent inertial time constant to 0.3s (PMSG pole pair number is 12, rotor-side converter inductance is 0.75mH); the doubly-fed induction generator (DFIG) uses a rotor-side converter (stator voltage directional control, reactive power regulation coefficient K) v =0.5) Reactive power generation increase, response time ≤0.05s (rotor side angular frequency base value is 377rad / s, reactive power generation increase ≥0.5pu during fault).

[0075] In the energy storage system, a dual closed-loop control system with an outer voltage loop and an inner current loop is adopted, and the PI parameter K of the outer voltage loop is... p =5、K i =0.05, current inner loop PI parameter K p =2、K i =0.1, DC bus fluctuation ≤5%.

[0076] Example:

[0077] Grid-based energy storage converters are a fundamental scenario for verifying the core capabilities of grid-based control in autonomous voltage build-up and fault ride-through. The topology adopts a four-layer architecture: energy storage unit - bidirectional DC / DC converter - VSC - LCL - AC grid. The energy storage unit uses a 1MW / 0.5kV lead-acid battery pack to ensure rapid discharge within 0.05s in case of fault. The bidirectional DC / DC converter is a Buck-Boost topology, with inductance calculated using the critical inductance formula and a capacitor of 10mF, meeting the requirement of DC voltage fluctuation ≤5%. The VSC is a two-level three-phase full-bridge converter with six 4000V / 2000A IGBT modules (switching frequency of 4950Hz) and a rated capacity of 2MVA, integrating synchronous control and CLC limiting modules. The LCL filter parameters are determined through engineering calculations as L1=0.1345mH, L2=0.1345mH, filter capacitor of 115.85μF, damping resistor of 0.508Ω, and resonant frequency of 900Hz, which can control the current harmonic content within 3%. Each component transmits control signals through optical fiber with a delay of ≤10μs to ensure coordinated operation.

[0078] The control strategy adopts a multi-mode adaptive architecture. During normal grid connection, virtual synchronous generator control is activated, with virtual inertia J=8.43kg·m², damping coefficient D=0.05, and primary frequency regulation coefficient k. f =50, outputting the phase angle through the rotor motion equation, with a reactive power loop AVR proportional coefficient Ku=1, achieving zero steady-state error voltage control; switching to PSL control in weak grid conditions, with an inertial time constant H=8.43s, simulating synchronous generator dynamics; switching to fixed-frequency control during faults, outputting a fixed frequency of 50Hz. The switching logic is based on grid SCR, frequency deviation (increasing inertia by 1.5 times when |Δf|>0.2Hz), and fault signal triggering, with a delay ≤50ms and no transient impact, such as... Figure 2 As shown, under weak power grid conditions, voltage fluctuation is ≤3%, and frequency is stable at 1 p.u.

[0079] The preset maximum current is 1.1 pu. In case of a fault, the d-axis priority limiting is used to ensure that the active power output is prioritized. When the fault signal is 1, the synchronization source switches from PSL to PLL (phase error ≤ 1°). After the fault is cleared, it switches back after 0.1 seconds of stabilization. Figure 3 (a) is the frequency response diagram during a short circuit. It can be seen that a three-phase short circuit fault occurs at 3s, and the frequency briefly drops to 0.95pu. After the fault is cleared, it recovers to 1.0pu within 0.3s, with fluctuation ≤0.02pu, which meets the frequency reference support requirements of fixed frequency control. Figure 3 (b) is the DC bus voltage diagram during short circuit. It can be seen that the voltage fluctuation range during the fault is 0.95~1.07pu, which does not exceed the safety threshold (1.0~1.12pu). The energy storage system quickly smooths out the fluctuation through the DC / DC converter, verifying the effectiveness of the voltage outer loop-current inner loop dual closed-loop control. Figure 3 (c) is the AC bus current diagram during short circuit. It can be seen that the peak current during fault is ≤1.1pu, the CLC limiting is effective and avoids current overshoot from damaging the IGBT module, which reflects the control logic of d-axis priority limiting. Figure 3 (d) is the active power diagram during short circuit. It can be seen that the active power drops from 0.2pu to 0 during the fault. After the fault is cleared, it recovers to the rated value within 300ms. The commutation overlap angle γ = 55° < 60°, and there is no commutation failure. Figure 3 (e) is the reactive power diagram during the short circuit. It can be seen that the reactive power rapidly increases to 0.2pu during the fault, supporting the recovery of the grid connection point voltage, and verifying the adjustment effect of the VSG reactive power loop AVR proportional coefficient Ku=1. Figure 3 (f) is the DC power diagram during a short circuit. It can be seen that during a fault, the DC power fluctuation is ≤ ±0.1 pu, and the energy storage unit discharges rapidly within 0.05 s, mitigating the power shortfall, which meets the design specification of DC fluctuation ≤ 5%. Therefore, from... Figure 3The method proposed in this invention can be seen to have the effects of current limiting, frequency / voltage stabilization, and rapid power recovery.

[0080] In the off-grid autonomous voltage build-up test (0.5 pu load applied in 1 second), the frequency fluctuation was ≤0.02 pu, and the voltage stabilized at 1 p.u. The grid-connected short-circuit test verified the fault ride-through capability. The simulation efficiency of the average value model (AC side controlled voltage source, DC side controlled current source + 2 mF capacitor) was improved by 8 times, and the time taken was 15 seconds in a 10-second duration. The errors of d-axis current and active power were ≤5%, which fully demonstrates the engineering applicability of the method proposed in this invention.

[0081] The grid-type photovoltaic converter focuses on active power reserve and frequency support functions. Its topology is based on an energy storage model with a photovoltaic array and an MPPT module superimposed on top. The photovoltaic array has a maximum power of 1.02MW, an open-circuit voltage of 1.24kV, a short-circuit current of 1.07kA, a series resistance of 0.02Ω, a parallel resistance of 1000Ω, a reference irradiance of 1000W / m², and a temperature of 25℃. Maximum power point tracking is achieved through the MPPT module. The active power reserve control hardware is a Boost converter (250μF inductor, 10mF capacitor). The photovoltaic array is connected to the DC bus through the Boost converter to achieve V... mpp Run on the right.

[0082] The core of the control strategy is the active power reserve logic, which is acquired in real time through the MPPT module. With V mpp Set backup power Target voltage for (Working at V) mpp On the right side, to prevent the voltage from falling below the inverter start-up threshold V when sunlight intensity drops. in =0.8V mpp ),Will The deviation from the actual voltage is fed into the PI controller (Kp=2, Ti=0.1) to adjust the duty cycle of the Boost converter, enabling rapid release of reserve power. During normal grid connection, the photovoltaic system operates in MPPT mode, with energy storage smoothing out fluctuations; when the frequency drops, it rapidly reduces... To V mpp Release ΔP with a response time ≤0.1s, which meets the requirements of GB / T 38983.1-2020.

[0083] The fault protection adopts the CLC limiting and synchronous source switching mechanism. In view of the intermittent characteristics of photovoltaic output, a power prediction module is added. When the predicted photovoltaic output drops by more than 10%, the energy storage discharge is activated in advance to avoid excessive fluctuations in DC bus voltage. Figure 4(a) is the frequency diagram of inertial response and primary frequency regulation test. It can be seen that at 5s, the grid frequency drops by 0.1Hz, and the frequency drops from 1.0pu to 0.98pu. After the photovoltaic active power reserve is released, it recovers to 0.995pu within 0.1s, and the overshoot is ≤0.01Hz. Figure 4 (b) is the AC bus current diagram. It can be seen that the DC voltage drops from 1.08pu (1.339kV) to 1.0pu (1.24kV), while the AC voltage stabilizes at 0.95~1.0pu. There is no risk of inverter shutdown, which verifies the voltage regulation logic of the active power reserve control on the right side of Vmpp. Figure 4 (c) is the AC bus current diagram. It can be seen that the peak current is ≤1.1pu. The CLC limiting effectively suppresses the fault current and ensures the current stability during active power generation. Figure 4 (d) is the active power diagram, which shows that the photovoltaic active power increased from 0.85pu (0.867MW) to 1.0pu (1.02MW), with a response time of ≤0.1s; Figure 4 (e) is the reactive power diagram, which shows that the reactive power fluctuation is ≤ ±0.02pu. The energy storage system works together to smooth out the fluctuation and ensure power quality. Figure 4 (f) is the DC-side power diagram. It can be seen that the DC-side power follows the changes in photovoltaic active power with a fluctuation range of ≤5%, which verifies the adjustment accuracy of the PI controller (Kp=2, Ti=0.1) of the Boost converter. Figure 4 (g) is the d-axis current graph. It can be seen that the d-axis current tracks the active power generation command and has no obvious overshoot, which reflects the control effect of proportional limiting. Figure 4 The (h) plot shows the q-axis current, which is stable between 0.2 and 0.4 pu, indicating stable supporting voltage, consistent with the reactive power regulation logic. Therefore, from... Figure 4 As can be seen from this, the method proposed in this invention has the synergistic effect of photovoltaic active power reserve control and primary frequency regulation.

[0084] Figure 5 (a) is the frequency diagram of the three-phase short circuit fault. It can be seen that the three-phase short circuit fault occurs at 5s, the frequency drops briefly to 0.98pu, and recovers to 1.0pu within 0.2s after the fault is cleared. The fluctuation is ≤0.015pu, and the frequency reference function of the fixed frequency control is significant. Figure 5 (b) is the AC / DC bus voltage diagram. It can be seen that the AC voltage drops to a minimum of 0.8 pu, and the DC voltage fluctuates between 0.9 and 1.05 pu. The energy storage system rapidly discharges to support the voltage and avoid voltage collapse. Figure 5 (c) is the AC bus current diagram. It can be seen that the peak current during a fault is ≤1.1pu. The CLC limiting and precise triggering limits the fault current and protects the power electronic devices. Figure 5 (d) is the active power diagram, which shows that the active power dropped from 1.0 pu to 0, and recovered to the rated value within 300 ms after the fault was cleared, with no power surge. Figure 5 (e) is the reactive power diagram, which shows that the reactive power is increased to 0.2 pu, supporting the rapid recovery of the grid connection point voltage and verifying the response speed of reactive power regulation; Figure 5 (f) is the DC-side power diagram. It can be seen that the DC-side power fluctuation is ≤ ±0.2 pu, indicating that the photovoltaic and energy storage work together to smooth out the fluctuations, meeting the DC bus stability requirements. Therefore, from... Figure 5 As can be seen from the method proposed in this invention, the CLC limiting and synchronous source switching mechanism can effectively suppress short-circuit current, and the energy storage synergy ensures stable recovery of voltage and power.

[0085] The grid-connected direct-drive wind turbine is based on inertial synchronization and fault ride-through, with a topology of wind turbine-PMSG-machine-side converter-grid-side grid-connected VSC-LCL-grid. The wind turbine has a rated wind speed of 11 m / s, a cut-in wind speed of 3 m / s, a cut-out wind speed of 25 m / s, and a tip speed ratio λ = 8~15; the PMSG has a rated power of 2MW, a stator voltage of 0.69kV, 12 pole pairs, a stator resistance of 0.01pu, and a rotor with permanent magnet excitation (no windings); the machine-side converter is a two-level topology (0.75mH inductance) using rotor flux-oriented vector control to achieve maximum wind energy tracking; the grid-side VSC is a grid-connected topology (0.335mH inductance) integrating inertial synchronization control; and a dynamic DC discharge resistor R... damp =1.1Ω, and the surplus power is consumed during a fault.

[0086] The core of the control strategy is inertial synchronization + inertia transfer. Inertial synchronization control is used on the grid side to establish a linkage between DC voltage and output angular frequency. The per-unit value of the DC voltage is input to the integral controller, and the output phase angle is used for PWM modulation, so that the grid-side converter exhibits the characteristics of a synchronous generator; an inertia transfer link is introduced on the generator side, which is superimposed on the active power reference value. A 0.1s low-pass filter is connected in series (to suppress high-frequency interference), increasing the equivalent inertial time constant from 0.1s to 0.3s, and utilizing the kinetic energy of the wind turbine to enhance frequency support. In addition, a stabilization control (high-pass filter Tp=0.1s, KPSS=1) is added on the grid side to increase electrical damping; a three-stage 0.1s low-pass filter is added on the turbine side to adjust the power phase and improve the damping coefficient.

[0087] The fault protection is optimized for the fault characteristics of the wind turbine. When the AC voltage is ≤0.87pu and the DC voltage is ≥1.07pu, the fault signal is 1, the synchronization source switches from inertial synchronization to PLL, the CLC limiting adopts d-axis priority, and the energy leakage resistor is put into operation to avoid DC overvoltage. Figure 6(a) is the active power response diagram when the direct-drive wind turbine is connected to the grid during a fault. It can be seen that a three-phase short circuit fault occurs at 6s, and the active power drops from 1.0pu to 0.2pu. After the fault is cleared, it recovers to 1.0pu within 1s. The inertia transfer link releases the kinetic energy of the wind turbine to support the power recovery. Figure 6 (b) is the reactive power response diagram, which shows that the reactive power increased to 0.5 pu during the fault period, quickly supporting the grid connection point voltage and verifying the reactive power regulation logic on the rotor side. Figure 6 (c) is the AC voltage RMS waveform. It can be seen that the voltage dropped to a minimum of 0.6 pu and recovered to 0.95 pu within 0.5 seconds after the fault was cleared, showing a significant voltage support effect. Figure 6 (d) is the d-axis and q-axis current curve. It can be seen that the peak d-axis current is ≤1.1 pu, and the q-axis current is stable between 0.4 and 0.6 pu. The CLC limiting and inertial synchronization control work together to avoid current overshoot. Therefore, from... Figure 6 As can be seen, the method proposed in this invention is effective in DC voltage-angular frequency linkage-energy discharge devices.

[0088] Comparing the effects of different control modes: In the inertia transfer mode alone, the DC voltage synchronized with the frequency change, the active power generation increased by 0.02 pu; in the inertia transfer + primary frequency regulation mode, the reserved pitch angle was reduced from 0.5° to 0.3°, the active power generation increased by 0.04 pu, and the frequency regulation effect was improved by 1 time; the active power and DC voltage error were ≤5%, the simulation time of 100 wind turbine systems was shortened from 120 minutes to 15 minutes, and the efficiency was improved by 8 times.

[0089] The dual-end flexible DC system focuses on the scenario of transmitting new energy to the open sea. The topology adopts an architecture of onshore grid-connected converter - 30km DC line - offshore grid-connected converter - wind farm. Each MMC converter station has a capacity of 475MVA, 152 sub-modules per phase (capacitor 2800μF), 50mH bridge arm inductance, and a DC voltage of 640kV. The DC line is a submarine cable with distributed parameters R=0.0275Ω, L=0.201mH, and C=0.612μF (automatically calculated by PSCAD according to the cross-sectional diagram). The onshore converter adopts grid-connected control (constant DC voltage + constant AC voltage), and the offshore converter adopts grid-connected Vf control (constant frequency 50Hz, constant AC voltage 230kV). The DC side is equipped with a discharge device (Rdamp=1.1Ω), which is put into operation when the voltage is ≥1.05pu.

[0090] The control strategy is designed differently for each converter station: the onshore converter has a constant DC voltage (640kV, PI parameters Kp=4, Ki=0.05) and a constant AC voltage (230kV, Kp=1, Ki=0.1) in the outer power loop, and a current inner loop with PI parameters Kp=0.65, Ki=0.025. The output is limited to ±1p.u., and an active power limiting circuit is added to reduce the active power input when the voltage exceeds the limit. The offshore converter adopts Vf control, with virtual inertia J=8.43kg·m² and damping coefficient D=0.05. The third harmonic (amplitude 0.15) is superimposed to improve the DC voltage utilization rate by 15%. The circulating current suppression controller has PI parameters Kp=0.8, Ki=0.01 to eliminate the second harmonic circulating current. The startup process is optimized as follows: the onshore converter is engaged in 0.2s (with a 100Ω current-limiting resistor in series), and the offshore converter is engaged in 0.6s. The DC voltage rises smoothly from 0 to 640kV without overshoot (≤5%). Figure 7 As shown, the wind farm starts up in 1.5 seconds, and the active power rises smoothly from 0 to 900MW without overshoot.

[0091] The fault protection primarily addresses the DC overvoltage problem. When the onshore AC system fails, energy cannot be delivered, the DC voltage rises, and the energy dissipation device activates within 0.05 seconds, consuming surplus power. For example... Figure 8 and Figure 9 As shown, P1 is the active power at the output side of bus 1, and P2 is the active power at the output side of bus 2. At 7s, the three-phase short circuit on the AC bus 1 side of the onshore converter lasts for 0.15s, and the active power drops to 300MW, while the power of the energy dissipation device reaches 600MW. The DC voltage rises from 640kV to 690kV (1.08pu) and then drops back quickly. After the fault is cleared, the active power recovers to 900MW in 1s. In the back-to-back converter scenario (short circuit at the sending end for 0.15s), the DC voltage drops to 570kV (0.89pu), while the load-side voltage remains at 0.9pu, indicating the flexibility of the control mode.

[0092] The grid-connected doubly-fed induction generator (DFIG) is designed for high-proportion wind power grid connection. Its topology adopts a wind turbine-DFIG-rotor-side / grid-side converter-LCL-grid architecture. The DFIG has a rated power of 2MW, stator voltage of 0.69kV, rotor voltage of 0.2kV, 3 pole pairs, and stator and rotor resistances of 0.01pu and 0.015pu, respectively. Rotor-side parameters are converted to stator-side parameters. The rotor-side converter uses stator voltage-oriented control (0.1mH inductance), and the grid-side converter is a grid-connected VSC (0.335mH inductance). The startup sequence references the official PSCAD model: 0.7s for grid-side converter to start and build up voltage, 0.9s for turbine-side converter to generate excitation current, and closing the circuit breaker when the voltage difference across the circuit breaker is <5%. After closing, the wind turbine switches to torque control 0.5s later to avoid startup shock.

[0093] The core of the control strategy is rotor-side voltage support + grid-side self-synchronization, with the rotor side using... The generator generates additional reactive power to support the grid connection point voltage. Ignoring stator resistance, the rotor current's d-axis component controls the stator voltage's q-axis component, and vice versa. The voltage regulator output serves as the rotor current command. On the grid side, PSL control is employed, calculating the phase angle based on the synchronous generator's motion equations (H=8.43s, D=0.05), ensuring stable power angles under weak grid conditions. Furthermore, wind power control is incorporated on the turbine side, fitting the wind energy utilization coefficient C using a 25-coefficient matrix. p The mechanical power is calculated by combining the tip speed ratio and the pitch angle. The pitch angle controller PI parameters are Kp=400, Ki=0.001, with a maximum value of 25° and a minimum value of 0°. When the wind speed exceeds the rated wind speed, the power is limited to 1 p.u.

[0094] For fault protection targeting the overcurrent characteristics of the doubly fed wind turbine rotor, a rotor-side crowbar circuit is added. In case of a fault, the rotor current is limited to ≤1.2pu, and the grid-side CLC limiting is activated, and the synchronization source is switched from PSL to PLL. Figure 10 (a) is the AC voltage effective value response diagram of the grid-connected fault of the doubly fed wind turbine. It can be seen that a three-phase short circuit fault occurred at 6s, and the AC voltage dropped to a minimum of 0.1pu. After the fault was cleared, it recovered to 1.0pu within 1.5s, and the reactive power support voltage on the rotor side was restored. Figure 10 (b) is the active power waveform diagram. It can be seen that the active power dropped from 1.0 pu to 0.2 pu. After the fault was cleared, it recovered to the rated value within 1.5s. The rotor speed released kinetic energy to support the power transition. Figure 10 (c) is the reactive power waveform diagram. It can be seen that during the fault period, the reactive power increased to 0.4 pu, rapidly raising the grid connection point voltage, verifying the regulation effect of the stator voltage directional control; therefore, from Figure 10 As can be seen from the present invention, after the method proposed in this invention restores the rated power, it meets the stability requirements for high-proportion wind power grid connection.

[0095] Comparison of performance at different wind speeds: Wind energy utilization coefficient C at a rated wind speed of 11 m / s p =0.48, output power 2MW; at low wind speed of 5m / s, C p =0.45, output power 0.5MW, tracking maximum wind energy; dq axis current and active power error ≤5%, simulation time of 10 wind turbine systems reduced from 60min to 8min, efficiency improved by 7.5 times, indicating that the method proposed in this invention is adaptable to different working conditions.

[0096] To address the issues of poor adaptability to weak power grids and high commutation failure rate of traditional grid-connected SLCC converter valves, the grid-type SLCC DC transmission system constructs a collaborative topology of 12-pulse LCC converter valve unit, grid-type SVG unit, and DC-side smoothing reactor. This topology adapts to scenarios with a high proportion of new energy access and achieves stable system operation through precise modeling.

[0097] In terms of topology design, the 12-pulse LCC converter valve unit consists of two 6-pulse LCCs connected in series, with the midpoint grounded via a 10Ω low impedance. It is paired with an SFZ11-31500 / 220 transformer (rated capacity 31.5MVA, short-circuit impedance 8%), using YY-YY wiring. The grid-type SVG unit is directly connected in parallel to the AC bus, integrating a virtual synchronous generator controller and current limiting control. The IGBT module is consistent with the LCC converter valve to ensure coordination. The DC-side smoothing reactor is a dry-type hollow type (rated current 3kA, inductance 80mH), which suppresses DC pulsation and isolates high-frequency disturbances.

[0098] The control strategy is centered on virtual synchronous generator control. The virtual inertia (0.5~2.0 kg·m²) is adaptively adjusted according to the system frequency change rate, and the active power damping coefficient (5~20 pu) is optimized in real time through a proportional-derivative controller to achieve autonomous voltage and frequency support. At the same time, a closed-loop coordination between SVG and LCC commutation voltage is established to maintain commutation voltage stability. In case of a fault, CLC limiting is activated to achieve rapid switching of PSL / PLL (delay ≤50ms), and stability is restored within 300ms.

[0099] like Figure 11 As shown in the PSCAD simulation, after the injection of harmonic interference, the DC side voltage is stable during normal operation of the system, and the sinusoidal nature of the AC voltage at the receiving end is good.

[0100] This invention also proposes an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. It should be noted that when the processor executes the computer program, it corresponds to the specific steps of the method provided in this invention, possessing the corresponding functional modules and beneficial effects for executing the method. Technical details not described in detail in this embodiment can be found in the method provided in this invention.

[0101] This invention also proposes a computer-readable storage medium storing a computer program. It should be noted that when the computer program is executed by a processor, it corresponds to the specific steps of the method provided in this invention, possessing the corresponding functional modules and beneficial effects for executing the method. Technical details not described in detail in this embodiment can be found in the method provided in this invention.

[0102] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A synchronous control and modeling method for a grid-type converter, characterized in that, include: S1. Construct a grid-type converter topology, which includes a front-end energy unit, a VSC unit, a DC energy storage unit, and an AC filter unit; S2. Based on the grid-type converter topology, a multi-mode synchronous control strategy is designed for the control of the synchronous generator. When the grid short-circuit ratio is greater than the first threshold and there is no fault, the virtual synchronous generator mode is adopted; when the voltage drop is greater than the second threshold, fixed-frequency control is adopted; when the frequency deviation is greater than the third threshold, inertial synchronous control is activated. S3. Implement CLC limiting and PSL / PLL synchronous source coordinated protection in current limiting control. Based on the converter voltage and current dynamic equation, obtain the d and q axis current reference values, and then obtain the current reference value magnitude. Different limiting strategies are adopted for different scenarios. S4. Adopting the principle of fundamental frequency dynamic preservation and switching detail ignoring, an average value model adapted to two-level VSC and MMC multi-topology is established. S5. Design specific control strategies for photovoltaic, wind turbine, and energy storage systems to achieve synergistic control effects.

2. The synchronous control and modeling method for a grid-type converter according to claim 1, characterized in that, In step S1, the front-end energy unit includes an adaptive energy storage unit with a rated power of 1MW and a rated voltage of 0.5kV, a photovoltaic array with a maximum power of 1.02MW and an open-circuit voltage of 1.24kV, a direct-drive wind turbine with a rated power of 2MW and a generator voltage of 0.69kV, and a doubly-fed wind turbine with a rated power of 2MW and an outlet bus voltage of 33kV. The VSC unit includes a two-level topology with 6 IGBT modules and an MMC topology with 152 sub-modules; the switching frequency of the IGBT modules is 4950Hz, and the capacitance of the sub-modules is 2800μF and the bridge arm inductance is 50mH. The DC energy storage unit includes a bidirectional DC / DC converter and a smoothing capacitor; the bidirectional DC / DC converter is in Buck-Boost mode, with an inductor of 250μF and a capacitor of 10mF; the two-level topology of the smoothing capacitor is 2mF, and the MMC topology is 1.28mF. The AC filtering unit includes an LCL filter; the total inductance of the LCL filter is 0.269mH, the filter capacitor is 115.85μF, and the damping resistor is 0.508Ω; among which, the first inductor L1=0.1345mH and the second inductor L2=0.1345mH.

3. The synchronous control and modeling method for a grid-type converter according to claim 1, characterized in that, In step S2, in the virtual synchronous generator mode, a virtual inertia J = 8.43 kg·m², a damping coefficient D = 0.05, and a primary frequency regulation coefficient k are introduced. f =50, used to provide inertial support during normal operation; In fixed-frequency control, a fixed 50Hz frequency signal is output as the frequency reference source for the local power grid and is applied in fault emergency scenarios. In inertial synchronous control, the angular frequency of the grid-side converter is linked to the DC voltage. In a wind turbine system, when the wind energy captured by the turbine increases (i.e., the DC voltage rises), the angular frequency of the grid-side converter is synchronously increased; conversely, when the wind energy captured by the turbine decreases (i.e., the DC voltage decreases), the angular frequency of the grid-side converter is synchronously decreased. The real-time rotational speed signal of the turbine is acquired, filtered for noise by a low-pass filter, and then multiplied by an adjustment coefficient K. c The inertia-transmitted power compensation is obtained and superimposed on the active power reference value of the grid-side converter. Based on the angular frequency obtained by linkage, the phase angle command of the grid-side converter output voltage is calculated by integration. Combined with the active power reference value after superimposed inertia compensation, the voltage amplitude command is determined. The phase angle command and the voltage amplitude command are input together into the PWM modulation module to control the switching action of the grid-side converter, adjust the output power and voltage phase of the AC side, and at the same time use the wind turbine inertia to buffer power fluctuations.

4. The synchronous control and modeling method for a grid-type converter according to claim 1, characterized in that, In step S3, the CLC limiting and PSL / PLL synchronous source coordinated protection is based on the converter voltage and current dynamic equations as follows: ； ； in, This refers to the inductance value of the filter inductor on the output side of the converter. , These represent the d-axis and q-axis components of the converter output current, respectively. , These represent the d-axis and q-axis components of the converter bridge arm output voltage, respectively. , These represent the d-axis and q-axis components of the grid connection point voltage, respectively. This is the equivalent resistance of the filter inductor on the output side of the converter. Angular frequency; When the current reference value magnitude When the current exceeds the preset maximum value, CLC limiting is activated; where, , , These are the reference values ​​for the d-axis and q-axis currents, respectively. In wind turbine scenarios, d-axis priority limiting is used, i.e. , ; STATCOM scenarios use q-axis priority limiting; general scenarios use proportional limiting; After limiting, corresponding fault signals are obtained based on different scenarios. When the fault signal is 1, the synchronization source is switched from PSL to PLL. When the fault signal is 0 and stable for 0.1s, it is switched back to PSL.

5. The synchronous control and modeling method for a grid-type converter according to claim 1, characterized in that, In step S4, for the two-level VSC scenario, the average value model is established, including: using a controlled voltage source on the AC side. Equivalent, of which The modulation ratio, This is the DC bus voltage. The fundamental initial phase angle of the AC output voltage of the converter. Angular frequency; controlled current source used on the DC side. Equivalent to the equivalent capacitance, where To measure the output power in AC mode, the equivalent capacitance on the DC side is set to 2mF. For MMC scenarios, the average value model is established including: a controlled voltage source on the AC side. Equivalent This refers to the number of submodules in a single bridge arm of the MMC. The voltage of the submodule capacitor is 1.28mF. The DC side is equivalent to a controlled current source and an equivalent capacitor.

6. The synchronous control and modeling method for a grid-type converter according to claim 1, characterized in that, In step S5, in the photovoltaic system, the maximum power point voltage V of the photovoltaic cell is used. mpp Right-side active power reserve control, reserve power for Target voltage for ,in Maximum power; the Boost converter is adjusted by a PI controller, and the standby release response time is ≤0.1s; MPPT is achieved using the perturbation-observation method, and ≥0.04pu of active power is generated when the frequency drops by 0.1Hz; In the wind turbine system, the active power reference value of the direct-drive wind turbine is superimposed on the turbine side, and a 0.1s low-pass filter is connected in series, which increases the equivalent inertial time constant to 0.3s. Doubly fed wind turbines generate reactive power through rotor-side converters with a response time of ≤0.05s; In the energy storage system, a dual closed-loop control system with an outer voltage loop and an inner current loop is adopted, and the PI parameter K of the outer voltage loop is... p =5、K i =0.05, current inner loop PI parameter K p =2、K i =0.1, DC bus fluctuation ≤5%.

7. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the synchronous control and modeling method for the grid-type converter according to any one of claims 1 to 6.

8. A computer-readable storage medium storing a computer program, characterized in that, The computer program, when run by the processor, executes the synchronous control and modeling method for the grid-type converter as described in any one of claims 1 to 6.

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