SVG control method for improving stability of weak power grid of new energy station

Abstract

The application discloses an SVG control method for improving the stability of a weak power grid of a new energy station, and belongs to the technical field of new energy grid connection stability control, power electronic equipment modeling and parameter optimization. The SVG control method comprises setting the phase-locked loop bandwidth and the system short-circuit ratio of the new energy station, sampling, power synchronous control, voltage outer loop control and a virtual resistance control link, and finally obtaining three-phase modulation waves. In the setting, sequence impedance modeling and D segmentation are used to realize visual solution of a multi-parameter coupling stability domain, and the stability domain of two parameters is obtained. The method has high parameter setting precision, is suitable for engineering working condition operation requirements, realizes accurate selection and stability control optimization of the SVG of the new energy station under the weak power grid, and greatly improves the grid connection stability and dynamic response performance of the station under the weak power grid working condition. The control is upgraded only through algorithm optimization, and no additional hardware equipment is needed, thereby saving engineering cost.

Description

Technical Field

[0001] This invention belongs to the technical fields of new energy grid-connected stability control, power electronic equipment modeling and parameter optimization. It relates to an SVG control method to improve the stability of weak grids in new energy power plants, and particularly to a grid-based SVG control architecture method for improving the stability of weak grids in new energy power plants. Background Technology

[0002] With the large-scale centralized grid connection of new energy sources such as wind power and photovoltaics, the power system's electronic characteristics are becoming increasingly prominent, the grid short-circuit ratio is continuously decreasing, and weak grid operation scenarios with low short-circuit ratios, weak damping, and low inertia are becoming the norm. The mainstream grid-connected equipment for new energy power plants is the grid-synchronized inverter, whose operation is highly dependent on phase-locked loops (PLLs) to achieve grid synchronization. Under weak grid conditions, it is extremely prone to safety and stability problems such as PLL instability, low-frequency power oscillations, and voltage collapse, which seriously restrict the safe and stable operation of new energy power plants and the interconnected power grid.

[0003] Static var generators (SVG) are core reactive power compensation and grid stability support devices in new energy power plants. Traditional grid-connected SVGs can only passively respond to grid disturbances in the mode of current source, without active voltage build-up and damping support capabilities. Their effect on improving the stability of weak grids is limited. Although impedance analysis can effectively characterize the interactive coupling characteristics between power electronic equipment and the grid, it can only achieve stability determination under fixed operating conditions and cannot obtain the global stability range of parameters. Eigenvalue analysis relies on solving the system state matrix, which has high computational complexity for high-order systems and makes it difficult to visualize the joint stability domain of multiple parameters. The SVG (Static Var Generator) has the potential for autonomous voltage building, virtual inertia support, and active damping adjustment, making it a core device for solving the stability problem of weak power grids. The D-segmentation method, as a classic method for solving the parameter stability domain, can divide the multidimensional parameter space into stable and unstable domains by crossing the critical condition of the imaginary axis of the characteristic equation. It has the advantages of high computational efficiency, intuitive results, and adaptability to multi-parameter coupled analysis, and is widely used in parameter tuning and stability boundary solving of power electronic control systems.

[0004] Currently, several academic papers have studied the SVG grid-connected stability control and D-segmentation method for new energy power plants, for example: 1. An article titled "PI Parameter Design and Stability Domain Analysis of Inverters Based on D-Segmentation Method under Weak Grids," *Automation of Electric Power Systems*, 2020, Vol. 15, pp. 139-147. Based on the D-segmentation method, the article obtains the PI parameter stability domain of grid-connected inverters under weak grids that simultaneously meet multiple performance indicators such as phase angle margin, gain margin, current loop bandwidth, and short-circuit ratio, and presents it graphically. However, the structure is simple, does not consider phase-locked loops, and is based on traditional grid-connected inverters for analysis, thus failing to improve the phase-locked loop instability situation in weak grids.

[0005] 2. An article titled "Impedance Modeling and Stability Analysis of Grid-Based Static Var Generators for New Energy Power Plants," published in the Journal of Electrical Engineering, 2026, Vol. 3, pp. 849-864. This article focuses on analyzing the negative damping distribution characteristics of the SVG output impedance and systematically discusses the influence of different SVG modes on wind farm stability. However, it cannot characterize the parameter design boundaries or the degree of improvement in phase-locked loop bandwidth margin.

[0006] 3. The Chinese invention patent document (publication number CN120879734A) published on June 26, 2025, entitled "Multi-site grid-connected configuration method and system with grid-type inverters and grid-type converters", proposes a multi-site grid-connected configuration method and system with grid-type inverters and grid-type converters. It uses the D-segmentation method to describe the quantitative relationship between equivalent grid impedance, grid-type converter capacity and location, and system stability margin, and accurately designs the grid-type converter configuration scheme under the given stability margin requirements. However, this invention mainly determines the minimum necessary capacity and optimal location configuration of the grid-type converter, but cannot solve the stability problem caused by phase-locked loop instability in new energy power stations.

[0007] Based on the above literature, the existing technology has the following shortcomings: 1. Existing research mainly focuses on the optimization of control strategies and performance improvement of single-type SVG, while there is a lack of research on the impedance mechanism and field-level systematic comparison of SVG with network control architecture; 2. Traditional power grid stability analysis methods have obvious shortcomings. Impedance analysis can only determine the stability under fixed-point operating conditions and cannot obtain the stability interval of the entire parameter domain. Eigenvalue analysis relies on solving the state matrix of a high-order system, which has extremely high computational complexity and makes it difficult to achieve visualization analysis of multi-parameter coupled stability domains, and cannot guide the optimization design of SVG parameters.

[0008] 3. Existing comparative studies on SVG stability do not clearly define the relationship between the system short-circuit ratio (SCR) and the phase-locked loop bandwidth. The coupled stability constraint mechanism has poor matching between formula derivation and numerical implementation, making it difficult to adapt to the stability control requirements of weak power grids in engineering practice, and unable to effectively solve the problem of oscillation and instability of new energy power plants under weak grids. Summary of the Invention

[0009] The technical problem this invention aims to solve is the lack of clarity regarding the adaptation mechanism of SVG in weak grids, the significant limitations in stability analysis, and the absence of precise basis for parameter design in existing technologies. This invention provides an SVG control method to improve the stability of renewable energy power plants in weak grid conditions. Through precise modeling, global stability domain solution, and parameter boundary tuning, it achieves accurate selection and optimized stability control of SVG for renewable energy power plants under weak grid conditions, significantly improving the grid connection stability and dynamic response performance of power plants under weak grid operating conditions.

[0010] The technical solution of the present invention is as follows.

[0011] An SVG control method for improving the stability of weak grids in renewable energy power plants is disclosed. The system applying this method includes an equipment side and a grid side. The equipment side includes the renewable energy power plant and the grid-connected SVG main circuit. The topology of the renewable energy power plant includes a first DC-side voltage source, a three-phase full-bridge inverter, and a three-phase... The filter, the topology of the SVG main circuit includes a second DC-side voltage source, an SVG three-phase full-bridge inverter, and a three-phase... connected in sequence. The filter; the grid side includes a three-phase line impedance and a three-phase power grid; the output terminals of the energy station and the grid-connected SVG main circuit are connected to the grid connection point PCC, and then connected to the three-phase power grid through the three-phase line impedance; The steps of the SVG control method are as follows: Step 1: Given the phase-locked loop bandwidth of the new energy power station Compared to system short circuit ratio ; Step 2, sample three phases Filter output voltage and output current and through Transformation to obtain αβ axis output voltage v α ,v β and αβ axis output current i α , i β After Transformation to obtain dq axis output voltage v d ,v q and dq axis output current i d ,i q ; active power is calculated and reactive power ; Step 3, active power and reactive power To obtain the phase angle, a power synchronization control circuit is implemented. and voltage reference The dq axis reference voltage is denoted as... , ,Pick = and order ; Step 4: Obtain the result through voltage outer loop control combined with virtual resistance control. shaft current reference Then, through the current inner loop control stage, the result is obtained. Axis Modulated Wave Then proceed with the reverse Transformation, Inverse The transformation yields a three-phase modulation wave; the switching on and off of each switch in the two three-phase full-bridge inverters is controlled based on the three-phase modulation wave.

[0012] Preferably, the bandwidth of the phase-locked loop for the new energy power station described in step 1 is... Compared to system short circuit ratio Parameter design is performed, and the D-segmentation method is applied to plot continuous critical stability curves on a two-dimensional parameter plane to obtain the parameter stability region that ensures stable system operation. Within this parameter stability region, the phase-locked loop bandwidth is selected. And the corresponding system short-circuit ratio (SCR) to achieve stable operation of the system under weak power grid conditions.

[0013] Preferably, the parameter design steps are as follows: Step 1.1: The three-phase full-bridge inverter in the power station is referred to as the power station inverter; Sequence impedance modeling was performed on the grid-connected SVG and the power station inverter, and the impedance of the grid-connected SVG was sampled. Equivalent impedance of the inverter at the power station Three-phase line impedance ; Step 1.2, based on the network SVG impedance Equivalent impedance of the power station inverter The impedance of the new energy power station was calculated. The calculation formula is:

[0014] In the formula, a,b These represent the number of three-phase full-bridge inverters and the number of grid-connected SVG units in the new energy power station, respectively, with a=5 and b=1. According to the impedance of new energy power stations and three-phase line impedance The closed-loop characteristic equation is obtained. ; Step 1.3: Obtain the phase-locked loop bandwidth based on the closed-loop characteristic equation. The expression for the system short-circuit ratio (SCR):

[0015] In the formula, This is the rated output line voltage of the inverter at the power station. For the rated power of new energy power stations, It is the power frequency angular frequency. Here, ω is the perturbation angular frequency, and j is the imaginary part in units. The bandwidth of the phase-locked loop The calculation formula is:

[0016] Step 1.4, based on the phase-locked loop bandwidth obtained in Step 1.3 The expression for the system short-circuit ratio (SCR) is given, with the SCR as the horizontal axis and the phase-locked loop bandwidth as the vertical axis. The vertical axis represents the perturbation angular frequency in logarithmic coordinates. from Change to Using several uniform logarithmically spaced sampling points, a line is plotted in a plane coordinate system. The curve, will The curve represents the bandwidth of the phase-locked loop. By finding the parameter stability region boundary of the system short-circuit ratio (SCR), we obtain the parameter stability region that enables the system to operate stably.

[0017] Preferably, the When plotting the curve, the bandwidth of the phase-locked loop is... The parameter range is 30-300Hz, and the short-circuit ratio (SCR) parameter range is 1.2-6.

[0018] Preferably, the power output in step 2 and reactive power The calculation formulas are as follows: .

[0019] Preferably, the phase angle described in step 3 and voltage reference The expressions are as follows:

[0020] In the formula, These are active power reference and reactive power reference, respectively. These are the angular frequency reference and the output voltage reference, respectively. These are the droop coefficients for the active power control system and the reactive power control system, respectively.

[0021] Preferably, step 4 is described shaft current reference The expression is:

[0022] In the formula, k pv k iv Here, represents the proportional and integral coefficients of the voltage outer-loop PI controller, respectively, and s is the Laplace operator. For virtual resistance; The Axis Modulated Wave The expression is:

[0023] In the formula, k pi k ii These are the proportional and integral coefficients of the current inner-loop PI controller, respectively. and These are the decoupling coefficient and the feedforward coefficient, respectively.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention completes the impedance modeling and global stability comparison analysis of SVG, clarifies the adaptation mechanism and damping characteristics differences of the two types of SVG under weak grid conditions, solves the problem of single research and lack of comparison in the existing technology, and effectively improves the weak grid stability of new energy power plants by adopting the grid SVG control architecture proposed in this invention, and provides a theoretical basis for the accurate selection of SVG equipment in weak grids. 2. This invention introduces the D-segmentation method to conduct stability analysis of new energy grid-connected systems, breaking through the technical bottlenecks of traditional impedance analysis for point determination and eigenvalue analysis for complex calculations, and can achieve... Visual solution of multi-parameter coupled stability domain, accurately dividing the stable and unstable regions of the system, with high parameter tuning accuracy, adaptable to engineering operating conditions; 3. This invention clarifies the advantages of SVG in supporting weak grid stability, effectively weakening the capacitive negative damping effect of weak grids and suppressing low-frequency oscillations of the system, significantly improving the safe and stable operation level of high-proportion new energy weak grid connection systems, and achieving control upgrades only through algorithm optimization without the need for additional hardware equipment, thus saving engineering costs. Attached Figure Description

[0025] Figure 1 This is a topology diagram of the SVG grid connection system for new energy power stations used in this invention.

[0026] Figure 2 This is a system control block diagram of the SVG network used in this invention.

[0027] Figure 3 The bandwidth of the phase-locked loop that does not use the method of this invention is The three-phase voltage waveform of PCC when the system short-circuit ratio SCR=2. Figure 4 The bandwidth of the phase-locked loop when using the method of this invention is The three-phase waveform of PCC with a system short-circuit ratio SCR=2. Figure 5 This is a schematic diagram illustrating the division of stable boundaries and stable regions using the parameter design method of the present invention. Figure 6 The bandwidth of the phase-locked loop using the method of this invention is The three-phase voltage and current waveforms of the PCC system with a short-circuit ratio SCR=2. Figure 7 The bandwidth of the phase-locked loop using the method of this invention is The three-phase voltage and current waveforms of the PCC system with a short-circuit ratio SCR=2. Detailed Implementation

[0028] The following is a detailed description of this embodiment with reference to the accompanying drawings.

[0029] Figure 1 This is a topology diagram of a new energy power plant grid-connected system using the grid-connected SVG of the present invention. As shown in the diagram, the system using the method of the present invention includes an equipment side and a grid side. The equipment side includes the new energy power plant and the grid-connected SVG main circuit. The topology of the new energy power plant includes a first DC voltage source, a three-phase full-bridge inverter, and a three-phase inverter connected in sequence. The filter, the topology of the SVG main circuit includes a second DC-side voltage source, an SVG three-phase full-bridge inverter, and a three-phase... connected in sequence. The filter; the grid side includes a three-phase line impedance and a three-phase power grid; the output terminals of the energy station and the grid-connected SVG main circuit are connected to the grid connection point PCC, and then connected to the three-phase power grid through the three-phase line impedance.

[0030] exist Figure 1 Above, 10 is the first DC-side voltage source, 20 is the three-phase full-bridge inverter circuit of the power station, and 30 is the three-phase... Filter, 40 is the second DC-side voltage source, 50 is the SVG three-phase full-bridge inverter, 60 is the three-phase... The filter has a three-phase line impedance of 70 and a three-phase power grid impedance of 80. The voltage of the first DC-side voltage source. Three-phase for the station The inductance on the bridge arm side of the filter, Three phases The filter capacitor of the filter, Three phases The passive damping resistor of the filter, Three phases The inductance on the bridge arm side of the filter, The inductance is the impedance of a three-phase line.

[0031] In this embodiment, the main circuit parameters are: the grid-connected inverter parameters are: the voltage of the first DC-side voltage source is: Three phases The inductance on the bridge arm side of the filter is =35e-6H, three-phase The filter capacitor is =1.34mF, three-phase The passive damping resistor of the filter is =0.0625Ω; the parameters of the SVG network are: three phases The inductance on the bridge arm side of the filter is =35e-6H; the inductance in the three-phase line impedance is =36.669uH

[0032] Figure 2 This is a system control block diagram of the SVG network used in this invention. Figure 2 Therefore, the present invention provides an SVG control method for improving the stability of weak power grids in new energy power plants. The steps of the SVG control method are as follows: Step 1: Given the phase-locked loop bandwidth of the new energy power station Compared to system short circuit ratio .

[0033] In this embodiment, the bandwidth of the phase-locked loop of the new energy power station described in step 1 is... Compared to system short circuit ratio Parameter design is performed, and the D-segmentation method is applied to plot continuous critical stability curves on a two-dimensional parameter plane to obtain the parameter stability region that ensures stable system operation. Within this parameter stability region, the phase-locked loop bandwidth is selected. And the corresponding system short-circuit ratio (SCR) to achieve stable operation of the system under weak power grid conditions.

[0034] The steps for parameter design are as follows: Step 1.1: The three-phase full-bridge inverter in the power station is referred to as the power station inverter; Sequence impedance modeling was performed on the grid-connected SVG and the power station inverter, and the impedance of the grid-connected SVG was sampled. Equivalent impedance of the inverter at the power station Three-phase line impedance .

[0035] Step 1.2, based on the network SVG impedance Equivalent impedance of the power station inverter The impedance of the new energy power station was calculated. The calculation formula is:

[0036] In the formula, a,b These represent the number of three-phase full-bridge inverters and the number of grid-connected SVG units in the new energy power station, respectively, with a=5 and b=1.

[0037] According to the impedance of new energy power stations and three-phase line impedance The closed-loop characteristic equation is obtained. .

[0038] Step 1.3: Obtain the phase-locked loop bandwidth based on the closed-loop characteristic equation. The expression for the system short-circuit ratio (SCR):

[0039] In the formula, This is the rated output line voltage of the inverter at the power station. For the rated power of new energy power stations, It is the power frequency angular frequency. Let ω be the perturbation angular frequency, and j be the imaginary part in units.

[0040] The bandwidth of the phase-locked loop The calculation formula is:

[0041] Step 1.4, based on the phase-locked loop bandwidth obtained in Step 1.3 The expression for the system short-circuit ratio (SCR) is given, with the SCR as the horizontal axis and the phase-locked loop bandwidth as the vertical axis. The vertical axis represents the perturbation angular frequency in logarithmic coordinates. from Change to Using 600 uniformly logarithmically spaced sampling points, a line is plotted in a plane coordinate system. The curve, will The curve represents the bandwidth of the phase-locked loop. By finding the parameter stability region boundary of the system short-circuit ratio (SCR), we obtain the parameter stability region that enables the system to operate stably.

[0042] The When plotting the curve, the bandwidth of the phase-locked loop is... The parameter range is 30-300Hz, and the short-circuit ratio (SCR) parameter range is 1.2-6.

[0043] Step 2, sample three phases Filter output voltage and output current and through Transformation to obtain αβ axis output voltage v α ,v β and αβ axis output current i α , i β After Transformation to obtain dq axis output voltage v d ,v q and dq axis output current i d ,i q ; active power is calculated and reactive power .

[0044] In this embodiment, the power output and reactive power The calculation formulas are as follows: .

[0045] Step 3, active power and reactive power To obtain the phase angle, a power synchronization control circuit is implemented. and voltage reference The dq axis reference voltage is denoted as... , ,Pick = and order .

[0046] In this embodiment, the phase angle and voltage reference The expressions are as follows:

[0047] In the formula, These are active power reference and reactive power reference, respectively. These are the angular frequency reference and the output voltage reference, respectively. These are the droop coefficients for the active power control system and the reactive power control system, respectively.

[0048] Step 4: Obtain the result through voltage outer loop control combined with virtual resistance control. shaft current reference Then, through the current inner loop control stage, the result is obtained. Axis Modulated Wave Then proceed with the reverse Transformation, Inverse The transformation yields a three-phase modulation wave; the switching on and off of each switch in the two three-phase full-bridge inverters is controlled based on the three-phase modulation wave.

[0049] In this embodiment, the shaft current reference The expression is:

[0050] In the formula, k pv k iv Here, represents the proportional and integral coefficients of the voltage outer-loop PI controller, respectively, and s is the Laplace operator. For virtual resistance; The Axis Modulated Wave The expression is:

[0051] In the formula, k pi k ii These are the proportional and integral coefficients of the current inner-loop PI controller, respectively. and These are the decoupling coefficient and the feedforward coefficient, respectively.

[0052] To demonstrate the beneficial effects of the present invention, simulations were performed.

[0053] Figure 3 The bandwidth of the phase-locked loop that does not employ the method of this invention The PCC three-phase voltage waveforms with a system short-circuit ratio SCR=2 show that the PCC three-phase voltages are unstable and the system is unstable.

[0054] Figure 4 The phase-locked loop bandwidth when using the method of the present invention The PCC three-phase waveform with a system short-circuit ratio SCR=2 can be seen from the figure, indicating that the system can operate stably under weak network conditions.

[0055] Figure 5 This diagram illustrates the division of the stability boundary and stability region using the parameter design method of this invention. As can be seen from the diagram, the phase-locked loop bandwidth is obtained by applying the parameter design method of this invention. By analyzing the parameter stability domain boundary curves of the system short-circuit ratio (SCR), the phase-locked loop bandwidth for stable system operation can be obtained. The parameter stability region of the system short-circuit ratio SCR.

[0056] Figure 6 The bandwidth of the phase-locked loop that does not employ the method of this invention The three-phase voltage and current waveforms of the PCC with a short-circuit ratio SCR=2 are unstable because they are located in the unstable region, and the system becomes unstable.

[0057] Figure 7 The bandwidth of the phase-locked loop using the method of this invention is The three-phase voltage and current waveforms of the PCC when the system short-circuit ratio SCR=2. At this time, since it is in the stable region, the system operates stably.

Claims

1. An SVG control method for improving the stability of a weak grid at a renewable energy power station, wherein the system applying this method includes an equipment side and a grid side, the equipment side including the renewable energy power station and the grid-connected SVG main circuit, and the topology of the renewable energy power station including a first DC-side voltage source, a three-phase full-bridge inverter, and a three-phase... The filter, the topology of the SVG main circuit includes a second DC-side voltage source, an SVG three-phase full-bridge inverter, and a three-phase... connected in sequence. The filter; the grid side includes a three-phase line impedance and a three-phase power grid; the output terminals of the energy station and the grid-connected SVG main circuit are connected to the grid connection point PCC, and then connected to the three-phase power grid through the three-phase line impedance; Its features are, The steps of the SVG control method are as follows: Step 1: Given the phase-locked loop bandwidth of the new energy power station Compared to system short circuit ratio ; Step 2, sample three phases Filter output voltage and output current and through Transformation to obtain αβ axis output voltage v α ,v β and αβ axis output current i α ,i β After Transformation to obtain dq axis output voltage v d ,v q and dq axis output current i d ,i q ; active power is calculated and reactive power ; Step 3, active power and reactive power To obtain the phase angle, a power synchronization control circuit is implemented. and voltage reference ; Let the dq axis reference voltage be denoted as , ,Pick = and order ; Step 4: Obtain the result through voltage outer loop control combined with virtual resistance control. shaft current reference Then, through the current inner loop control stage, it is obtained Axis Modulated Wave Then proceed with the reverse Transformation, Inverse The transformation yields a three-phase modulation wave; the switching on and off of each switch in the two three-phase full-bridge inverters is controlled based on the three-phase modulation wave.

2. The SVG control method for improving the stability of weak power grids in new energy power plants according to claim 1, characterized in that, The bandwidth of the phase-locked loop for the new energy power station described in step 1 Compared to system short circuit ratio Parameter design is performed, and the D-segmentation method is applied to plot continuous critical stability curves on a two-dimensional parameter plane to obtain the parameter stability region that ensures stable system operation. Within this parameter stability region, the phase-locked loop bandwidth is selected. And the corresponding system short-circuit ratio (SCR) to achieve stable operation of the system under weak power grid conditions.

3. The SVG control method for improving the stability of weak power grids in new energy power plants according to claim 2, characterized in that, The steps for parameter design are as follows: Step 1.1: The three-phase full-bridge inverter in the power station is referred to as the power station inverter; Sequence impedance modeling was performed on the grid-connected SVG and the power station inverter, and the impedance of the grid-connected SVG was sampled. Equivalent impedance of the inverter at the power station Three-phase line impedance ; Step 1.2, based on the SVG impedance of the network Equivalent impedance of the power station inverter The impedance of the new energy power station was calculated. The calculation formula is: In the formula, a,b These represent the number of three-phase full-bridge inverters and the number of grid-connected SVG units in the new energy power station, respectively, with a=5 and b=1. According to the impedance of new energy power stations and three-phase line impedance The closed-loop characteristic equation is obtained. ; Step 1.3: Obtain the phase-locked loop bandwidth based on the closed-loop characteristic equation. The expression for the system short-circuit ratio (SCR): In the formula, This is the rated output line voltage of the inverter at the power station. For the rated power of new energy power stations, It is the power frequency angular frequency. Here, ω is the perturbation angular frequency, and j is the imaginary part in units. The bandwidth of the phase-locked loop The calculation formula is: Step 1.4, based on the phase-locked loop bandwidth obtained in Step 1.3 The expression for the system short-circuit ratio (SCR) is given, with the SCR as the horizontal axis and the phase-locked loop bandwidth as the vertical axis. The vertical axis represents the perturbation angular frequency in logarithmic coordinates. from Change to Using several uniform logarithmically spaced sampling points, a line is plotted in a plane coordinate system. The curve, will The curve represents the bandwidth of the phase-locked loop. By finding the parameter stability region boundary of the system short-circuit ratio (SCR), we obtain the parameter stability region that enables the system to operate stably.

4. The SVG control method for improving the stability of weak power grids in new energy power plants according to claim 3, characterized in that, The When plotting the curve, the bandwidth of the phase-locked loop is... The parameter range is 30-300Hz, and the short-circuit ratio (SCR) parameter range is 1.2-6.

5. The SVG control method for improving the stability of weak power grids in new energy power plants according to claim 1, characterized in that, The power output described in step 2 and reactive power The calculation formulas are as follows: 。 6. The SVG control method for improving the stability of weak power grids in new energy power plants according to claim 1, characterized in that, The phase angle described in step 3 and voltage reference The expressions are as follows: In the formula, These are active power reference and reactive power reference, respectively. These are the angular frequency reference and the output voltage reference, respectively. These are the droop coefficients for the active power control system and the reactive power control system, respectively.

7. The SVG control method for improving the stability of weak power grids in new energy power plants according to claim 1, characterized in that, Step 4 shaft current reference The expression is: In the formula, k pv k iv Here, represents the proportional and integral coefficients of the voltage outer-loop PI controller, respectively, and s is the Laplace operator. For virtual resistance; The Axis Modulated Wave The expression is: In the formula, k pi k ii These are the proportional and integral coefficients of the current inner-loop PI controller, respectively. and These are the decoupling coefficient and the feedforward coefficient, respectively.

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