Method and system for full-power output of new energy unit and SVG (static var generator) under low short circuit ratio

Abstract

The invention discloses a method and a system for full-power transmission of a new energy unit and an SVG under a low short-circuit ratio, and the method comprises the steps: inputting the SVG into a machine end of the new energy unit in a low-short-circuit-ratio power system, and obtaining a machine end voltage of the new energy unit; calculating active power and reactive power emitted by the new energy unit; analyzing the relationship between the terminal voltage of the new energy unit and the active power, the reactive power and the infinite power supply voltage to obtain the relationship between the infinite power supply voltage and the new energy transmission power; and based on the relationship between the infinite power supply voltage and the new energy transmission power, determining that SVG is input to carry out reactive compensation on the machine end of the new energy unit, and enabling the transmission power of the new energy unit in the low-short-circuit-ratio power system to reach full power. The technical problem of grid-connected transmission power reactive power balance construction of the new energy station under the low short circuit ratio is solved.

Description

Technical Field

[0001] This invention relates to the field of power system safety and stability control, specifically to a method and system for new energy generating units and SVG to deliver full power under low short-circuit ratios. Background Technology

[0002] As the proportion of new energy sources such as wind power and photovoltaics in the power system gradually increases, a high proportion of new energy is becoming an important trend and key characteristic of power system development. The large number of new energy grid-connected devices using power electronic devices as interfaces significantly alters the characteristics of AC grids dominated by synchronous machines. Power electronic devices lack the mechanical inertia of synchronous machines and have poor disturbance rejection performance, resulting in a weakening of the electrical strength of AC grids connected to new energy sources. Especially when large-scale new energy power plants are connected to the AC grid, complex coupling relationships arise between new energy units and the AC grid, as well as among the new energy units themselves, leading to a series of stability issues.

[0003] The short-circuit ratio is commonly used to measure the strength of an AC power grid. Studies have found that the integration of new energy sources lowers the short-circuit ratio of grids previously dominated by thermal power. This decrease in the grid's short-circuit ratio leads to a reduction in system stability margin and the capacity of new energy sources to support power generation. These issues constrain the reactive power balance construction of new energy units at full power and limit testing methods for new energy sources under low short-circuit ratios. Therefore, researching reactive power balance construction schemes for new energy models in grids with low short-circuit ratios can effectively contribute to the development of new energy sources. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for new energy generating units and SVG to deliver full power at low short-circuit ratios, comprising:

[0005] In a power system with a low short-circuit ratio, an SVG is connected to the generator terminals of a new energy unit to obtain the generator terminal voltage of the new energy unit;

[0006] Calculate the active power and reactive power generated by the new energy unit;

[0007] By analyzing the relationship between the generator terminal voltage of the new energy unit and its active power, reactive power and infinite power supply voltage, the relationship between the infinite power supply voltage and the new energy transmission power is derived.

[0008] Based on the relationship between the infinite power supply voltage and the power transmission of new energy sources, it is determined that SVG will be used to perform reactive power compensation at the generator terminals of the new energy units, so that the power transmission of new energy units in the low short-circuit ratio power system can reach full power.

[0009] Furthermore, obtaining the terminal voltage of the new energy unit includes:

[0010] The terminal voltage of the new energy generating unit is obtained from the infinite power supply voltage, line impedance, and line current:

[0011]

[0012] in, For the terminal voltage of new energy generating units, The voltage of the power supply is infinite. R is the line current. S X is the line resistance. S Here, j represents the line inductance, and j is the imaginary unit.

[0013] Furthermore, the calculation of the active and reactive power generated by the new energy unit includes:

[0014] Assumption The apparent power delivered by the new energy generating unit to the infinite power source is calculated as follows:

[0015]

[0016] Where u is the amplitude of the generator terminal voltage of the new energy unit, θ is the phase of the generator terminal voltage of the new energy unit, and E is the amplitude of the infinite power supply voltage;

[0017] Separating the real part of apparent power (active power) and the imaginary part (reactive power) yields the expressions for active power P and reactive power Q:

[0018]

[0019] Where X represents the line inductance.

[0020] Furthermore, by analyzing the relationship between the generator terminal voltage and active power, reactive power, and infinite power supply voltage of the new energy unit, the relationship between the infinite power supply voltage and the new energy transmission power is derived, including:

[0021] In the expressions for active power P and reactive power Q, u 2 Moving the term to the left side of the equation yields:

[0022]

[0023] Z 2 =R 2 +X 2 Substituting into the above equation and summing the squares of the active and reactive terms, we obtain the fourth-order equation for the terminal voltage:

[0024] u 4 -(2PR+2QX+E 2 )u 2 +Z 2 (P 2 +Q2 ) = 0

[0025] Solving the equation yields the expression for the square of the terminal voltage:

[0026]

[0027] The square root can be used to find the voltage expression:

[0028]

[0029] Ignoring the line resistance R in a single-machine infinite system, we can obtain:

[0030]

[0031] The voltage expression is derived as follows:

[0032]

[0033] Keeping all parameters except active power constant, the relationship between terminal voltage and active power transmission of new energy sources is obtained using MATLAB.

[0034] Furthermore, based on the relationship between the infinite power supply voltage and the power transmission capacity of the new energy source, it is determined that SVG will be used to perform reactive power compensation at the generator terminals of the new energy unit, so that the power transmission capacity of the new energy unit in the low short-circuit ratio power system reaches full power, including:

[0035] Based on the relationship between the infinite power supply voltage and the power transmission capacity of new energy sources, we conclude that:

[0036] Z 2 Q 2 -2Xu 2 Q+(Z 2 P 2 -2PRu 2 -E 2 u 2 +u 4 ) = 0

[0037] Solving

[0038]

[0039] According to the above formula, by changing the reactive power at the generator terminal, the transmission power of the new energy generator unit can be changed, and the reactive power at the generator terminal can be compensated by SVG, so that the transmission power of the new energy generator unit in the low short-circuit ratio power system can reach full power.

[0040] This invention also provides a system for new energy generating units and SVG to deliver full power at low short-circuit ratios, comprising:

[0041] The generator terminal voltage acquisition module is used to input SVG at the generator terminal of new energy generating units in power systems with low short-circuit ratios and to acquire the generator terminal voltage of the new energy generating units.

[0042] The power calculation module is used to calculate the active power and reactive power generated by the new energy unit.

[0043] The voltage and power acquisition module is used to analyze the relationship between the generator terminal voltage of the new energy unit and the active power, reactive power and infinite power supply voltage, and to obtain the relationship between the infinite power supply voltage and the new energy transmission power.

[0044] The power transmission module is used to determine, based on the relationship between the infinite power supply voltage and the power transmission of new energy, to activate the SVG to perform reactive power compensation at the generator terminals of the new energy unit, so as to achieve full power transmission of the new energy unit in the low short-circuit ratio power system.

[0045] Furthermore, the terminal voltage acquisition module includes:

[0046] The generator terminal voltage calculation submodule is used to determine the generator terminal voltage of new energy generating units from the infinite power supply voltage, line impedance, and line current.

[0047]

[0048] in, For the terminal voltage of new energy generating units, The voltage of the power supply is infinite. R is the line current. S X is the line resistance. S Here, j represents the line inductance, and j is the imaginary unit.

[0049] Furthermore, the power calculation module includes:

[0050] Apparent power calculation submodule, used for assuming The apparent power delivered by the new energy generating unit to the infinite power source is calculated as follows:

[0051]

[0052] Where u is the amplitude of the generator terminal voltage of the new energy unit, θ is the phase of the generator terminal voltage of the new energy unit, and E is the amplitude of the infinite power supply voltage;

[0053] The power expression determination submodule is used to separate the real part of apparent power (active power) and the imaginary part (reactive power) to obtain expressions for active power P and reactive power Q:

[0054]

[0055] Where X represents the line inductance.

[0056] Furthermore, the power delivery module includes:

[0057] The term shifting submodule is used to shift the u in the expressions for active power P and reactive power Q. 2 Moving the term to the left side of the equation yields:

[0058]

[0059] The quartic equation yields a submodule used to obtain Z. 2 =R 2 +X 2 Substituting into the above equation and summing the squares of the active and reactive terms, we obtain the fourth-order equation for the terminal voltage:

[0060] u 4 -(2PR+2QX+E 2 )u 2 +Z 2 (P 2 +Q 2 ) = 0

[0061] Solving the equation yields the expression for the square of the terminal voltage:

[0062]

[0063] The square root can be used to find the voltage expression:

[0064]

[0065] Ignoring the line resistance R in a single-machine infinite system, we can obtain:

[0066]

[0067] The voltage expression deriving submodule is used to derive the voltage expression as follows:

[0068]

[0069] The relationship graph acquisition submodule is used to keep parameters other than active power constant and to obtain the relationship graph between generator terminal voltage and active power transmission of new energy through MATLAB.

[0070] Furthermore, the power delivery module includes:

[0071] The reactive power determination submodule is used to derive, based on the relationship between the infinite power supply voltage and the power transmitted from new energy sources, the following:

[0072] Z 2 Q 2 -2Xu 2 Q+(Z 2 P 2-2PRu 2 -E 2 u 2 +u 4 ) = 0

[0073] Solving

[0074]

[0075] According to the above formula, by changing the reactive power at the generator terminal, the transmission power of the new energy generator unit can be changed, and the reactive power at the generator terminal can be compensated by SVG, so that the transmission power of the new energy generator unit in the low short-circuit ratio power system can reach full power.

[0076] This invention provides a method and system for full-power transmission of renewable energy units and SVG under low short-circuit ratio. In low short-circuit ratio scenarios, SVG is connected at the generator terminal of the renewable energy unit. By adjusting the reactive power output of the SVG, the transmission power of the renewable energy power generation system can be improved, thus solving the technical problem of reactive power balance construction of renewable energy power plant grid connection transmission power under low short-circuit ratio. Attached Figure Description

[0077] Figure 1 This is a schematic flowchart of a method for powering new energy generating units and SVG at full power output under low short-circuit ratio according to an embodiment of the present invention.

[0078] Figure 2 This is a single-machine infinite bus system involved in the embodiments of the present invention;

[0079] Figure 3 This is a diagram showing the relationship between terminal voltage and active power transmission of new energy sources, as described in an embodiment of the present invention.

[0080] Figure 4 These are simulation results related to embodiments of the present invention;

[0081] Figure 5 This is a schematic diagram of the structure of a system provided by an embodiment of the present invention for a new energy unit and an SVG to deliver full power at a low short-circuit ratio. Detailed Implementation

[0082] Numerous specific details are set forth in the following description to provide a full understanding of the invention. However, the invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0083] This invention addresses low short-circuit ratio scenarios in power systems by increasing the transmission power of renewable energy generating units through the introduction of SVG (Static Var Generator) at the renewable energy generator terminal. First, a general analysis of the generator voltage, active power transmission, and reactive power transmission in the grid-connected renewable energy system after grid equivalence is required. Second, based on this general analysis, the relationship between the generator terminal voltage and the active power transmission, reactive power transmission, and grid-side power supply voltage is derived. Finally, based on the above analysis, it can be concluded that introducing SVG at the renewable energy generator terminal can change the transmission power of the renewable energy generating unit. Based on this, the present invention provides a method for renewable energy generating units and SVG to deliver full power under low short-circuit ratio conditions, such as... Figure 1 As shown, it includes the following steps:

[0084] Step S101: Connect the SVG at the generator terminal of the new energy unit in the low short-circuit ratio power system and obtain the generator terminal voltage of the new energy unit.

[0085] Single-machine infinite system such as Figure 2 As shown, the terminal voltage of a new energy generator unit can be obtained from the infinite power supply voltage, line impedance, and line current:

[0086]

[0087] in, For the terminal voltage of new energy generating units, The voltage of the power supply is infinite. R is the line current. S X is the line resistance. S Here, j represents the line inductance, and j is the imaginary unit.

[0088] Step S102: Calculate the active power and reactive power generated by the new energy unit.

[0089] Assumption The apparent power delivered by the new energy unit to the infinite power source can be calculated as follows:

[0090]

[0091] Where u is the amplitude of the generator terminal voltage of the new energy unit, θ is the phase of the generator terminal voltage of the new energy unit, and E is the amplitude of the infinite power supply voltage;

[0092] By separating the real part of apparent power (active power) and the imaginary part (reactive power), we can obtain the expressions for active power P and reactive power Q:

[0093]

[0094] Where X represents the line inductance.

[0095] Step S103: By analyzing the relationship between the generator terminal voltage of the new energy unit and the active power, reactive power and infinite power supply voltage, the relationship between the infinite power supply voltage and the new energy transmission power is obtained.

[0096] In the expressions for active power P and reactive power Q, u 2 Moving the term to the left side of the equation yields:

[0097]

[0098] Z 2 =R 2 +X 2 Substituting into the above equation and summing the squares of the active and reactive terms, we obtain the fourth-order equation for the terminal voltage:

[0099] u 4 -(2PR+2QX+E 2 )u 2 +Z 2 (P 2 +Q 2 ) = 0

[0100] Solving the equation yields the expression for the square of the terminal voltage:

[0101]

[0102] Taking the square root yields the voltage expression (ignoring negative terms):

[0103]

[0104] Since the line resistance in a single-machine infinite bus system is often small, we can ignore the line resistance R in the single-machine infinite bus system and obtain:

[0105]

[0106] The voltage expression is derived as follows:

[0107]

[0108] Keeping all parameters except active power constant, the relationship between terminal voltage and active power transmission of new energy sources is plotted using MATLAB, as shown below. Figure 3 As shown.

[0109] Step S104: Based on the relationship between the infinite power supply voltage and the new energy transmission power, determine to activate the SVG to perform reactive power compensation at the generator terminal of the new energy unit, so as to achieve full power transmission of the new energy unit in the low short-circuit ratio power system.

[0110] Based on the relationship between the infinite power supply voltage and the power transmission capacity of new energy sources, we conclude that:

[0111] Z 2 Q 2 -2Xu 2 Q+(Z 2 P 2 -2PRu 2 -E 2 u 2 +u 4 ) = 0

[0112] Solving

[0113]

[0114] As can be seen from the above formula, changing the reactive power at the generator end can change the transmission power of the new energy generator unit. The implementation of SVG can effectively compensate for the reactive power at the generator end, thereby improving the transmission power.

[0115] Considering that directly supplying 1 pu would have a significant impact on the power grid, it is recommended to increase the active power slope limit in actual use, such as 1 pu / s or 0.5 pu / s.

[0116] Based on electromagnetic software, the relationship between the transmitted power and the capacity of the SVG (Static Var Generator) when the short-circuit ratio (SCR) is 1.5 was studied. The simulation duration was 5 seconds, and the simulation step size was 0.01 seconds. The simulation results are as follows: Figure 4 As shown

[0117] Figure 4 It can be seen that: from t=0 to 2s, since the voltage of the infinite power supply is the same as that of the new energy generator, the power transmitted by the new energy generator to the infinite power grid is 0; starting from t=2s, the capacity of the SVG is increased from 0 to 0.4. It can be found that the terminal voltage of the new energy generator gradually increases from 1p.u. to 1.01pu. At the same time, under the active slope limit (0.5pu / s), the active power transmitted by the new energy increases synchronously, gradually increasing from 0 per unit value to 1 per unit value (t=4s).

[0118] The simulation results show that the introduction of SVG at the generator end of the new energy unit can improve the transmission power of the new energy unit. This verifies that the introduction of SVG at the generator end of the new energy unit can improve the transmission power of the new energy unit under low short-circuit ratio.

[0119] Based on the same inventive concept, this invention also provides a system 500 for full-power transmission of new energy units and SVG under low short-circuit ratios, such as... Figure 5 As shown, it includes:

[0120] Terminal voltage acquisition module 510 is used to input SVG at the generator terminal of new energy generating units in a low short-circuit ratio power system and acquire the generator terminal voltage of the new energy generating units.

[0121] The power calculation module 520 is used to calculate the active power and reactive power generated by the new energy unit.

[0122] The voltage and power acquisition module 530 is used to analyze the relationship between the generator terminal voltage of the new energy unit and the active power, reactive power and infinite power supply voltage, and to obtain the relationship between the infinite power supply voltage and the new energy transmission power.

[0123] The power transmission module 540 is used to determine, based on the relationship between the infinite power supply voltage and the power transmission of new energy, to activate the SVG to perform reactive power compensation at the generator terminal of the new energy unit, so as to achieve full power transmission of the new energy unit in the low short-circuit ratio power system.

[0124] Furthermore, the terminal voltage acquisition module includes:

[0125] The generator terminal voltage calculation submodule is used to determine the generator terminal voltage of new energy generating units from the infinite power supply voltage, line impedance, and line current.

[0126]

[0127] in, For the terminal voltage of new energy generating units, The voltage of the power supply is infinite. R is the line current. S X is the line resistance. S Here, j represents the line inductance, and j is the imaginary unit.

[0128] Furthermore, the power calculation module includes:

[0129] Apparent power calculation submodule, used for assuming The apparent power delivered by the new energy generating unit to the infinite power source is calculated as follows:

[0130]

[0131] Where u is the amplitude of the generator terminal voltage of the new energy unit, θ is the phase of the generator terminal voltage of the new energy unit, and E is the amplitude of the infinite power supply voltage;

[0132] The power expression determination submodule is used to separate the real part of apparent power (active power) and the imaginary part (reactive power) to obtain expressions for active power P and reactive power Q:

[0133]

[0134] Where X represents the line inductance.

[0135] Furthermore, the power delivery module includes:

[0136] The term shifting submodule is used to shift the u in the expressions for active power P and reactive power Q. 2 Moving the term to the left side of the equation yields:

[0137]

[0138] The quartic equation yields a submodule used to obtain Z. 2 =R 2 +X 2 Substituting into the above equation and summing the squares of the active and reactive terms, we obtain the fourth-order equation for the terminal voltage:

[0139] u 4 -(2PR+2QX+E 2 )u 2 +Z 2 (P 2 +Q 2 ) = 0

[0140] Solving the equation yields the expression for the square of the terminal voltage:

[0141]

[0142] The square root can be used to find the voltage expression:

[0143]

[0144] Ignoring the line resistance R in a single-machine infinite system, we can obtain:

[0145]

[0146] The voltage expression deriving submodule is used to derive the voltage expression as follows:

[0147]

[0148] The relationship graph acquisition submodule is used to keep parameters other than active power constant and to obtain the relationship graph between generator terminal voltage and active power transmission of new energy through MATLAB.

[0149] Furthermore, the power delivery module includes:

[0150] The reactive power determination submodule is used to derive, based on the relationship between the infinite power supply voltage and the power transmitted from new energy sources, the following:

[0151] Z 2 Q 2 -2Xu 2 Q+(Z 2 P 2 -2PRu 2 -E 2 u 2 +u4 ) = 0

[0152] Solving

[0153]

[0154] According to the above formula, by changing the reactive power at the generator terminal, the transmission power of the new energy generator unit can be changed, and the reactive power at the generator terminal can be compensated by SVG, so that the transmission power of the new energy generator unit in the low short-circuit ratio power system can reach full power.

[0155] This invention provides a method and system for full-power transmission of renewable energy units and SVG under low short-circuit ratio. In low short-circuit ratio scenarios, SVG is connected at the generator terminal of the renewable energy unit. By adjusting the reactive power output of the SVG, the transmission power of the renewable energy power generation system can be improved, thus solving the key technical problem of reactive power balance construction of renewable energy power plant grid connection transmission power under low short-circuit ratio.

[0156] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The present invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, produce implementations of the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0157] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0158] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0159] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A method for new energy unit and SVG to send out at full power under low short-circuit ratio, characterized in that, include: In a power system with a low short-circuit ratio, an SVG is connected to the generator terminals of a new energy unit to obtain the generator terminal voltage of the new energy unit; Calculate the active power and reactive power generated by the new energy unit; By analyzing the relationship between the generator terminal voltage of the new energy unit and its active power, reactive power and infinite power supply voltage, the relationship between the infinite power supply voltage and the new energy transmission power is derived. Based on the relationship between the infinite power supply voltage and the power transmission of new energy sources, it is determined that SVG will be used to perform reactive power compensation at the generator terminals of the new energy units, so that the power transmission of new energy units in the low short-circuit ratio power system can reach full power.

2. The method of claim 1, wherein, Obtaining the terminal voltage of the new energy generating unit includes: The terminal voltage of the new energy generating unit is obtained from the infinite power supply voltage, line impedance, and line current: wherein, V is the terminal voltage of the new energy unit, V is the voltage of the infinite power supply, I is the line current, R S R is the line resistance, X S L is the line inductance, and j is the imaginary unit.

3. The method of claim 1, wherein, The calculation of the active and reactive power generated by the new energy unit includes: Assume The apparent power delivered by the new energy unit to the infinite power source is calculated as: Where u is the amplitude of the generator terminal voltage of the new energy unit, θ is the phase of the generator terminal voltage of the new energy unit, and E is the amplitude of the infinite power supply voltage; Separating the real part of apparent power (active power) and the imaginary part (reactive power) yields the expressions for active power P and reactive power Q: Where X represents the line inductance.

4. The method of claim 1, wherein, By analyzing the relationship between the generator terminal voltage and active power, reactive power, and infinite power supply voltage of the aforementioned new energy generating units, the relationship between the infinite power supply voltage and the power transmitted by the new energy sources is derived, including: The expression for the active power P and the reactive power Q 2 Moving the term to the left side of the equation gives: Z 2 = R 2 + X 2 Substituting the above equation and squaring the active and reactive terms separately and adding them gives a fourth order equation for the terminal voltage: u 4 - (2PR + 2QX + E 2 )u 2 + Z 2 (P 2 + Q 2 ) = 0 Solving the equation yields the expression for the square of the terminal voltage: The square root can be used to find the voltage expression: Ignoring the line resistance R in a single-machine infinite system, we can obtain: The voltage expression is derived as follows: Keeping all parameters except active power constant, the relationship between terminal voltage and active power transmission of new energy sources is obtained using MATLAB.

5. The method of claim 1, wherein, Based on the relationship between the infinite power supply voltage and the power transmission capacity of new energy sources, it is determined that SVG will be used to perform reactive power compensation at the generator terminals of the new energy units, so as to achieve full power transmission capacity of the new energy units in the low short-circuit ratio power system, including: Based on the relationship between the infinite power supply voltage and the power transmission capacity of new energy sources, we conclude that: Z 2 Q 2 -2Xu 2 Q+(Z 2 P 2 -2PRu 2 -E 2 u 2 +u 4 ) = 0 Solving According to the above formula, by changing the reactive power at the generator terminal, the transmission power of the new energy generator unit can be changed, and the reactive power at the generator terminal can be compensated by SVG, so that the transmission power of the new energy generator unit in the low short-circuit ratio power system can reach full power.

6. A system for new energy unit and SVG to send out at full power under low short-circuit ratio, characterized in that, include: The generator terminal voltage acquisition module is used to input SVG at the generator terminal of new energy generating units in power systems with low short-circuit ratios and to acquire the generator terminal voltage of the new energy generating units. The power calculation module is used to calculate the active power and reactive power generated by the new energy unit. The voltage and power acquisition module is used to analyze the relationship between the generator terminal voltage of the new energy unit and the active power, reactive power and infinite power supply voltage, and to obtain the relationship between the infinite power supply voltage and the new energy transmission power. The power transmission module is used to determine, based on the relationship between the infinite power supply voltage and the power transmission of new energy, to activate the SVG to perform reactive power compensation at the generator terminals of the new energy unit, so as to achieve full power transmission of the new energy unit in the low short-circuit ratio power system.

7. The system of claim 6, wherein, Terminal voltage acquisition module, including: The generator terminal voltage calculation submodule is used to determine the generator terminal voltage of new energy generating units from the infinite power supply voltage, line impedance, and line current. wherein, V is the terminal voltage of the new energy unit, V is the voltage of the infinite power supply, I is the line current, R S X is the line resistance, X S L is the line inductance, and j is the imaginary unit.

8. The system of claim 6, wherein, The power calculation module comprises: The apparent power calculation sub-module is used for assuming The apparent power delivered by the new energy unit to the infinite power source is calculated as: Wherein, u is the amplitude of the new energy unit terminal voltage, θ is the phase of the new energy unit terminal voltage, E is the amplitude of the infinite power supply voltage; The power expression determination sub-module is used for separating the real part, i.e. the active power, and the imaginary part, i.e. the reactive power, of the apparent power to obtain the expression of the active power P and the reactive power Q: Wherein, X is the line inductance.

9. The system of claim 6, wherein, The power transmission module comprises: The item moving submodule is configured to move u 2 The item moving submodule is configured to move u The fourth-order equation obtaining submodule is configured to obtain a fourth-order equation of Z 2 = R 2 + X 2 Substitute the above formula and square the active term and the reactive term respectively and add them to obtain the fourth-order equation of the terminal voltage. u 4 - (2PR + 2QX + E 2 )u 2 + Z 2 (P 2 + Q 2 ) = 0 The equation can be solved to obtain the expression of the terminal voltage square: The square root can be used to obtain the voltage expression: The line resistance R in the single-machine infinite system can be ignored to obtain: The voltage expression obtaining sub-module is used for obtaining the voltage expression as: The relationship diagram obtaining sub-module is used for keeping the parameters except the active power unchanged, and obtaining the relationship diagram of the terminal voltage and the active power of the new energy transmission through matlab.

10. The system of claim 6, wherein, The power transmission module comprises: The reactive power determination sub-module is used for obtaining, based on the relationship between the infinite power supply voltage and the new energy transmission power: Z 2 Q 2 -2Xu 2 Q+(Z 2 P 2 -2PRu 2 -E 2 u 2 +u 4 )=0 The solution is According to the above formula, the transmission power of the new energy unit in the low short-circuit ratio power system can be changed by changing the terminal reactive power, the transmission power of the new energy unit can reach the full power by inputting the SVG to compensate the terminal reactive power.

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