Method and device for improving new energy transmission power in low-short-circuit-ratio electric power system

Abstract

The invention provides a method and system for improving new energy transmission power in a low-short-circuit-ratio electric power system, and the method comprises the steps: when the terminal voltage is smaller than a set voltage threshold value, according to the voltage threshold value, the current active power and the current reactive power of a new energy terminal, calculating the new energy transmission power according to the current active power and the current reactive power of the new energy terminal; calculating incremental reactive power to be input by new energy according to infinite power supply voltage, equivalent line resistance and equivalent line inductance which are determined when the new energy grid-connected system is equivalent to a single-machine infinite system; calculating a capacitance value of a capacitor to be input at a new energy machine end according to the incremental reactive power; and inputting at least one capacitor in a capacitor cluster of the new energy machine end according to the capacitance value until the new energy transmission power reaches the power threshold value. According to the method and the device, the reactive power is increased by adjusting the capacitance value of the new energy machine end, the transmission power of the new energy power generation system is improved to the full power, and the bottleneck of the transmission capacity of a traditional new energy power generation system is effectively broken through.

Description

Technical Field

[0001] This invention relates to the field of power system safety and stability control technology, and more specifically, to a method and apparatus for increasing the transmission power of new energy sources in power systems with 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 reduces the short-circuit ratio of grids that were originally dominated by thermal power. A decrease in the grid's short-circuit ratio leads to a reduction in system stability margin and the carrying capacity of new energy sources. Therefore, how to increase the transmission power of new energy sources under conditions of a low grid short-circuit ratio has become an urgent problem to be solved. Summary of the Invention

[0004] In order to address the technical problem that a decrease in the short-circuit ratio of the power grid will lead to a decrease in system stability margin and a decrease in the carrying capacity of new energy sources, the present invention provides a method and apparatus for improving the transmission power of new energy sources in a power system with a low short-circuit ratio.

[0005] According to one aspect of the present invention, the present invention provides a method for increasing the transmission power of new energy sources in a power system with a low short-circuit ratio, comprising:

[0006] The new energy grid-connected system is equivalent to a single-machine infinite system, and the infinite power supply voltage, equivalent line resistance, and equivalent line inductance of the single-machine infinite system are determined.

[0007] When the short-circuit ratio of the new energy grid-connected system is less than the set short-circuit ratio threshold, the generator terminal voltage, current active power and current reactive power of the new energy are obtained.

[0008] When the generator terminal voltage is less than the set voltage threshold, the incremental reactive power to be invested by the new energy source is calculated based on the voltage threshold, the current active power, the current reactive power, the infinite power supply voltage, the equivalent line resistance, and the equivalent line inductance. The voltage threshold is calibrated based on the new energy generator terminal voltage when the new energy transmission power reaches the power threshold.

[0009] Calculate the capacitance value of the capacitor to be connected at the new energy generator end based on the incremental reactive power;

[0010] At least one capacitor in the capacitor cluster at the new energy generator is connected according to the capacitance value until the new energy transmission power reaches the power threshold.

[0011] According to another aspect of the present invention, the present invention provides an apparatus for increasing the transmission power of new energy sources in a power system with a low short-circuit ratio, the apparatus comprising:

[0012] The grid equivalent module is used to convert the new energy grid-connected system into a single-machine infinite system, and to determine the infinite power supply voltage, equivalent line resistance, and equivalent line inductance of the single-machine infinite system.

[0013] The data acquisition module is used to acquire the generator terminal voltage, current active power, and current reactive power of the new energy source when the short-circuit ratio of the new energy grid-connected system is less than the set short-circuit ratio threshold.

[0014] The incremental reactive power module is used to calculate the incremental reactive power to be invested by the new energy source when the generator terminal voltage is less than the set voltage threshold, based on the voltage threshold, current active power, current reactive power, infinite power supply voltage, equivalent line resistance, and equivalent line inductance. The voltage threshold is calibrated based on the new energy generator terminal voltage when the new energy transmission power reaches the power threshold.

[0015] The reactive power capacitor module is used to calculate the capacitance value of the capacitor to be connected at the new energy generator end based on the incremental reactive power.

[0016] The capacitor input module is used to input at least one capacitor in the capacitor cluster of the new energy generator according to the capacitance value, until the power transmitted by the new energy reaches the power threshold.

[0017] According to another aspect of the present invention, a computer-readable storage medium is provided, the storage medium storing a computer program that, when executed by a processor, implements the methods described in any of the above aspects of the present invention.

[0018] According to another aspect of the present invention, an electronic device is provided, the electronic device comprising: a processor; a memory for storing executable instructions of the processor; the processor being configured to read the executable instructions from the memory and execute the instructions to implement the method described in any of the preceding aspects of the present invention.

[0019] The present invention discloses a method and apparatus for increasing the transmission power of renewable energy in power systems with low short-circuit ratios. The method includes: equating the renewable energy grid-connected system to a single-unit infinite power system; determining the infinite power supply voltage, equivalent line resistance, and equivalent line inductance of the single-unit infinite power system; when the short-circuit ratio of the renewable energy grid-connected system is less than a set short-circuit ratio threshold, acquiring the generator terminal voltage, current active power, and current reactive power of the renewable energy; when the generator terminal voltage is less than a set voltage threshold, calculating the incremental reactive power to be invested in the renewable energy based on the voltage threshold, current active power, current reactive power, infinite power supply voltage, equivalent line resistance, and equivalent line inductance; calculating the capacitance value of the capacitor to be invested at the generator terminal of the renewable energy based on the incremental reactive power; and investing at least one capacitor in the capacitor cluster at the generator terminal of the renewable energy based on the capacitance value, until the renewable energy transmission power reaches the power threshold. The method and apparatus, by investing capacitor reactive power compensation at the generator terminal of the renewable energy unit in a low short-circuit ratio power system scenario, can increase the transmission power of the renewable energy power generation system up to full power by adjusting the reactive power of the capacitor, effectively breaking through the bottleneck of the transmission capacity of traditional renewable energy power generation systems. Attached Figure Description

[0020] Exemplary embodiments of the present invention can be more fully understood by referring to the following figures:

[0021] Figure 1 A flowchart of a method for increasing the transmission power of new energy sources in a power system with a low short-circuit ratio according to a preferred embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of the equivalent model of a new energy grid-connected system according to a preferred embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of the relationship between the terminal voltage of new energy sources and the transmission power in the power grid equivalent model of a preferred embodiment of the present invention;

[0024] Figure 4 This is a schematic diagram of the equivalent model of the input capacitor at the new energy generator terminal in a new energy grid-connected system according to a preferred embodiment of the present invention;

[0025] Figure 5 This is a schematic diagram of simulation results according to a preferred embodiment of the present invention;

[0026] Figure 6 This is a schematic diagram of the structure of a device for increasing the transmission power of new energy sources in a power system with a low short-circuit ratio according to a preferred embodiment of the present invention.

[0027] Figure 7 This is a schematic diagram of the structure of an electronic device according to a preferred embodiment of the present invention. Detailed Implementation

[0028] Exemplary embodiments of the invention will now be described with reference to the accompanying drawings. However, the invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention. In the drawings, the same units / elements are referred to by the same reference numerals.

[0029] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.

[0030] Exemplary methods

[0031] Figure 1 This is a flowchart illustrating a method for increasing the transmission power of new energy sources in a power system with a low short-circuit ratio according to a preferred embodiment of the present invention. Figure 1 As shown, the method for increasing the transmission power of new energy sources in a power system with a low short-circuit ratio according to this preferred embodiment begins from step 101.

[0032] In step 101, the new energy grid-connected system is equivalent to a single-machine infinite power system, and the infinite power supply voltage, equivalent line resistance, and equivalent line inductance of the single-machine infinite power system are determined.

[0033] Figure 2 This is a schematic diagram of the equivalent model of a new energy grid-connected system according to a preferred embodiment of the present invention. Figure 2 As shown, if the new energy grid-connected system is equivalent to a single-unit infinite bus system, then the terminal voltage of the new energy unit can be obtained from the infinite power supply voltage, line impedance, and line current. The calculation formula is as follows:

[0034]

[0035] 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 This refers to the line inductance.

[0036] Assumption The apparent power delivered by the new energy unit to the infinite power source can be calculated as follows:

[0037]

[0038] Separating the real part of apparent power (active power) and the imaginary part (reactive power) yields expressions for active and reactive power (for simplicity, the subscript 's' of equivalent line resistance and equivalent line inductance is omitted, and the same applies below):

[0039]

[0040] By separating the real part of apparent power (active power) and the imaginary part (reactive power), we can obtain the expressions for active power and reactive power:

[0041]

[0042] Let u in the above equation 2 Moving the term to the left side of the equation yields:

[0043]

[0044] 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:

[0045] u 4 -(2PR+2QX+E 2 )u 2 +Z 2 (P 2 +Q 2 ) = 0

[0046] Solving the equation yields the expression for the square of the terminal voltage:

[0047]

[0048] Taking the square root yields the voltage expression (ignoring negative terms).

[0049]

[0050] Since the line resistance in a single-machine infinite bus system is often small and negligible, ignoring R, we can obtain:

[0051]

[0052] The voltage expression is derived as follows:

[0053]

[0054] Keeping all parameters except active power constant, the relationship between terminal voltage and active power transmission of new energy sources is plotted using MATLAB. Figure 3This is a schematic diagram illustrating the relationship between the terminal voltage of a new energy source and the transmitted power in a power grid equivalent model according to a preferred embodiment of the present invention. Figure 3 As shown, when the terminal voltage is 0.7 pu, the active power can reach its maximum value of 1 p.u. However, when the terminal voltage is less than 0.7 pu, the active power is less than its maximum value. The voltage threshold in this preferred embodiment is set according to this principle.

[0055] Furthermore, the fourth equation for the terminal voltage can be transformed into:

[0056] Z 2 Q 2 -2Xu 2 Q+(Z 2 P 2 -2PRu 2 -E 2 u 2 +u 4 ) = 0

[0057] Solving the above transformed equations yields:

[0058]

[0059] As can be seen from the above expression for reactive power, in the equivalent power grid model, when the equivalent line resistance, equivalent line inductance, equivalent line impedance, generator terminal voltage, and active power of the new energy generator are known, the corresponding reactive power of the new energy generator can be determined.

[0060] In step 102, when the short-circuit ratio of the new energy grid-connected system is less than the set short-circuit ratio threshold, the generator terminal voltage, current active power and current reactive power of the new energy are obtained.

[0061] In this preferred embodiment, the short-circuit ratio threshold is set based on an empirical value, such as 1.5.

[0062] In step 103, when the generator terminal voltage is less than the set voltage threshold, the incremental reactive power to be invested by the new energy source is calculated based on the voltage threshold, the current active power, the current reactive power, the infinite power supply voltage, the equivalent line resistance, and the equivalent line inductance. The voltage threshold is calibrated based on the generator terminal voltage of the new energy source when the new energy transmission power reaches the power threshold.

[0063] As described above, the voltage threshold of this preferred embodiment is based on Figure 3 The relationships shown are tuned.

[0064] Preferably, when the terminal voltage is less than a set voltage threshold, the incremental reactive power to be injected from new energy sources is calculated based on the voltage threshold, current active power, current reactive power, infinite power supply voltage, equivalent line resistance, and equivalent line inductance. The calculation formula is as follows:

[0065] ΔQ1=Q-Q1

[0066]

[0067] In the formula, ΔQ1 is the incremental reactive power to be put into operation, P1 and Q1 are the current active power and current reactive power of the new energy generator terminal, respectively, U is the voltage threshold, Q is the reactive power when the voltage of the new energy generator terminal reaches the voltage threshold, and E, R, X and Z are the power supply voltage of the single-machine infinite system, the equivalent line resistance, the equivalent line inductance and the equivalent line impedance, respectively.

[0068] In step 104, the capacitance value of the capacitor to be connected at the new energy generator terminal is calculated based on the incremental reactive power.

[0069] Preferably, the capacitance value of the capacitor to be connected at the new energy generator terminal is calculated based on the incremental reactive power, and the calculation formula is as follows:

[0070]

[0071] In the formula, C is the capacitance value of the capacitor to be connected to the new energy generator terminal, and ω is the angular frequency.

[0072] In step 105, at least one capacitor in the capacitor cluster of the new energy generator is connected according to the capacitance value until the new energy transmission power reaches the power threshold.

[0073] Preferably, at least one capacitor in the capacitor cluster at the new energy generator end is connected according to the capacitance value until the new energy transmission power reaches the power threshold, including setting an active power slope limit so that the new energy transmission power gradually increases according to the active power slope limit.

[0074] In this preferred embodiment, considering that direct active power supply to the power threshold has a significant impact on the power grid, it is preferable to add an active power slope limit, such as 1 pu / s or 0.5 pu / s, to ensure that the transmitted power gradually increases, thereby fully guaranteeing the stability of the power grid.

[0075] Figure 4 This is a schematic diagram of the equivalent model of the input capacitor at the generator end of a new energy grid-connected system according to a preferred embodiment of the present invention. Figure 4As shown, in this preferred embodiment, a capacitor cluster consisting of n capacitors is configured at the generator end of the new energy unit. By switching on and off the n capacitors to change the capacitors connected to the generator end of the new energy unit, corresponding reactive power compensation can be achieved, thereby increasing the transmission power of the new energy unit.

[0076] This preferred embodiment uses existing electromagnetic simulation software to simulate the relationship between the new energy transmission power and the size of the input capacitor when the short-circuit ratio (SCR) is 1.5. The simulation duration is 5 seconds, and the simulation step size is 0.01 seconds. Figure 5 This is a schematic diagram of simulation results according to a preferred embodiment of the present invention. Figure 5 As shown, from t=0 to 2s, since the voltage of the infinite power supply is the same as that of the renewable energy unit, the power transmitted by the renewable energy unit to the infinite power grid is 0. Starting from t=2s, the size of the connected capacitor is increased from 0 to 0.4. It can be observed that the voltage at the generator terminal of the renewable energy unit gradually increases from 1 p.u. to 1.01 p.u. Simultaneously, under the active power slope limitation (0.5 p.u. / s), the active power transmitted by the renewable energy unit increases synchronously, gradually increasing from 0 per unit value to 1 per unit value (t=4s). The simulation results show that connecting the capacitor at the generator terminal of the renewable energy unit can improve the power transmitted by the renewable energy unit, thus verifying the feasibility and reliability of the technical solution of the present invention, which can improve the power transmitted by the renewable energy unit under low short-circuit ratio by connecting the capacitor at the generator terminal of the renewable energy unit.

[0077] The preferred embodiment of this method for increasing the transmission power of new energy sources in a power system with a low short-circuit ratio involves adding capacitor reactive power compensation at the generator terminal of the new energy unit in a low short-circuit ratio scenario. By adjusting the reactive power of the capacitor, the transmission power of the new energy power generation system can be increased up to full power, effectively breaking through the bottleneck of the transmission capacity of traditional new energy power generation systems.

[0078] Exemplary device

[0079] Figure 6 This is a schematic diagram of a device for increasing the transmission power of new energy sources in a power system with a low short-circuit ratio according to a preferred embodiment of the present invention. Figure 6 As shown, the device 600 for increasing the transmission power of new energy sources in a power system with a low short-circuit ratio according to this preferred embodiment includes:

[0080] The power grid equivalent module 601 is used to convert the new energy grid-connected system into a single-machine infinite system and determine the infinite power supply voltage, equivalent line resistance and equivalent line inductance of the single-machine infinite system.

[0081] The data acquisition module 602 is used to acquire the generator terminal voltage, current active power and current reactive power of the new energy source when the short-circuit ratio of the new energy grid-connected system is less than the set short-circuit ratio threshold.

[0082] The incremental reactive power module 603 is used to calculate the incremental reactive power to be invested by the new energy source when the generator terminal voltage is less than the set voltage threshold, based on the voltage threshold, current active power, current reactive power, infinite power supply voltage, equivalent line resistance and equivalent line inductance. The voltage threshold is calibrated based on the new energy generator terminal voltage when the new energy transmission power reaches the power threshold.

[0083] The reactive power capacitor module 604 is used to calculate the capacitance value of the capacitor to be connected at the new energy generator end based on the incremental reactive power.

[0084] The capacitor input module 605 is used to input at least one capacitor in the capacitor cluster of the new energy generator according to the capacitance value, until the power transmitted by the new energy reaches the power threshold.

[0085] Preferably, when the terminal voltage is less than a set voltage threshold, the incremental reactive power module 603 calculates the incremental reactive power to be injected from the new energy source based on the voltage threshold, current active power, current reactive power, infinite power supply voltage, equivalent line resistance, and equivalent line inductance. The calculation formula is as follows:

[0086] ΔQ1=Q-Q1

[0087]

[0088] In the formula, ΔQ1 is the incremental reactive power to be put into operation, P1 and Q1 are the current active power and current reactive power of the new energy generator terminal, respectively, U is the voltage threshold, Q is the reactive power when the voltage of the new energy generator terminal reaches the voltage threshold, and E, R, X and Z are the power supply voltage of the single-machine infinite system, the equivalent line resistance, the equivalent line inductance and the equivalent line impedance, respectively.

[0089] Preferably, the reactive power capacitor module 604 calculates the capacitance value of the capacitor to be connected at the new energy generator end based on the incremental reactive power, and the calculation formula is as follows:

[0090]

[0091] In the formula, C is the capacitance value of the capacitor to be connected to the new energy generator terminal, and ω is the angular frequency.

[0092] Preferably, the capacitor input module 605 inputs at least one capacitor in the capacitor cluster of the new energy generator according to the capacitance value until the new energy transmission power reaches the power threshold, including setting an active power slope limit so that the new energy transmission power gradually increases according to the active power slope limit.

[0093] The preferred embodiment of the device for increasing the transmission power of new energy sources in a power system with a low short-circuit ratio and the method for increasing the transmission power of new energy sources in a power system with a low short-circuit ratio share the same steps as the steps of investing a capacitor at the new energy generator end, determining the capacitor value of the invested capacitor based on the calculated incremental reactive power to be invested by the new energy source, and switching the capacitor according to the capacitor value to increase the transmission power of the new energy source. The technical effects achieved are also the same, and will not be described again here.

[0094] Exemplary electronic devices

[0095] Figure 7 This is a schematic diagram of the structure of an electronic device according to a preferred embodiment of the present invention. Figure 7 As shown, the electronic device includes one or more processors 701 and memory 702.

[0096] The processor 701 may be a central processing unit (CPU) or other form of processing unit with data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions.

[0097] The memory 702 may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may include, for example, random access memory (RAM) and / or cache memory. The non-volatile memory may include, for example, read-only memory (ROM), hard disk, flash memory, etc. One or more computer program instructions may be stored on the computer-readable storage medium, and the processor 701 may execute the program instructions to implement the methods for increasing the transmission power of new energy sources in low short-circuit ratio power systems as described in the various embodiments disclosed above, and / or other desired functions. In one example, the electronic device may also include an input device 703 and an output device 704, these components being interconnected via a bus system and / or other forms of connection mechanisms (not shown).

[0098] In addition, the input device 703 may also include, for example, a keyboard, a mouse, etc.

[0099] The output device 704 can output various information to the outside. The output device 704 may include, for example, a display, a speaker, a printer, and a communication network and its connected remote output devices, etc.

[0100] Of course, for the sake of simplicity, Figure 7 Only some of the components of the electronic device relevant to this disclosure are shown, omitting components such as buses, input / output interfaces, etc. In addition, the electronic device may include any other suitable components depending on the specific application.

[0101] Exemplary computer program products and computer-readable storage media

[0102] In addition to the methods and apparatus described above, embodiments of this disclosure may also be computer program products comprising computer program instructions that, when executed by a processor, cause the processor to perform the steps in the methods for increasing the transmission power of new energy sources in a low short-circuit ratio power system as described in the "Exemplary Methods" section of this specification according to various embodiments of this disclosure.

[0103] The computer program product can be written in any combination of one or more programming languages ​​to perform the operations of the embodiments of this disclosure. The programming languages ​​include object-oriented programming languages ​​such as Java and C++, as well as conventional procedural programming languages ​​such as C or similar languages. The program code can be executed entirely on a user's computing device, partially on a user's computing device, as a standalone software package, partially on a user's computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0104] Furthermore, embodiments of this disclosure may also be computer-readable storage media storing computer program instructions that, when executed by a processor, cause the processor to perform the steps in the methods for increasing the transmission power of new energy sources in a low short-circuit ratio power system according to various embodiments of this disclosure as described in the "Exemplary Methods" section above.

[0105] The computer-readable storage medium may be any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may, for example, include, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatuses, or devices, or any combination thereof. More specific examples of readable storage media (a non-exhaustive list) include: electrical connections having one or more wires, portable disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0106] The basic principles of this disclosure have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this disclosure are merely examples and not limitations, and should not be considered as essential features of each embodiment of this disclosure. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the scope of this disclosure to the necessity of employing the aforementioned specific details for implementation.

[0107] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For system embodiments, since they largely correspond to method embodiments, the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0108] The block diagrams of devices, apparatuses, devices, and systems disclosed herein are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0109] The apparatus and methods of this disclosure may be implemented in many ways. For example, they may be implemented by software, hardware, firmware, or any combination of software, hardware, and firmware. The above-described order of steps for the methods is for illustrative purposes only, and the steps of the methods of this disclosure are not limited to the order specifically described above unless otherwise specifically stated. Furthermore, in some embodiments, this disclosure may also be implemented as a program recorded on a recording medium, the program including machine-readable instructions for implementing the methods according to this disclosure. Thus, this disclosure also covers recording media storing programs for performing the methods according to this disclosure.

[0110] It should also be noted that in the apparatus, devices, and methods of this disclosure, the components or steps are decomposable and / or recombinable. Such decomposition and / or recombination should be considered equivalent to the present disclosure. The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this disclosure. Therefore, this disclosure is not intended to be limited to the aspects shown herein, but rather to be carried out within the widest scope consistent with the principles and novel features disclosed herein.

[0111] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this disclosure to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations therein.

Claims

1. A method for increasing the transmission power of new energy sources in a power system with a low short-circuit ratio, characterized in that, The method includes: The new energy grid-connected system is equivalent to a single-machine infinite system, and the infinite power supply voltage, equivalent line resistance, and equivalent line inductance of the single-machine infinite system are determined. When the short-circuit ratio of the new energy grid-connected system is less than the set short-circuit ratio threshold, the generator terminal voltage, current active power and current reactive power of the new energy are obtained. When the generator terminal voltage is less than the set voltage threshold, the incremental reactive power to be invested by the new energy source is calculated based on the voltage threshold, the current active power, the current reactive power, the infinite power supply voltage, the equivalent line resistance, and the equivalent line inductance. The voltage threshold is calibrated based on the new energy generator terminal voltage when the new energy transmission power reaches the power threshold. Calculate the capacitance value of the capacitor to be connected at the new energy generator end based on the incremental reactive power; At least one capacitor in the capacitor cluster at the new energy generator is connected according to the capacitance value until the new energy transmission power reaches the power threshold.

2. The method according to claim 1, characterized in that, When the terminal voltage is less than the set voltage threshold, the incremental reactive power to be injected from new energy sources is calculated based on the voltage threshold, current active power, current reactive power, infinite power supply voltage, equivalent line resistance, and equivalent line inductance. The calculation formula is as follows: ΔQ1=Q-Q1 In the formula, ΔQ1 is the incremental reactive power to be put into operation, P1 and Q1 are the current active power and current reactive power of the new energy generator terminal, respectively, U is the voltage threshold, Q is the reactive power when the voltage of the new energy generator terminal reaches the voltage threshold, and E, R, X and Z are the power supply voltage of the single-machine infinite system, the equivalent line resistance, the equivalent line inductance and the equivalent line impedance, respectively.

3. The method according to claim 1, characterized in that, The capacitance value of the capacitor to be connected at the new energy generator terminal is calculated based on the incremental reactive power, and the calculation formula is as follows: In the formula, C is the capacitance value of the capacitor to be connected to the new energy generator terminal, and ω is the angular frequency.

4. The method according to claim 1, characterized in that, At least one capacitor in the capacitor cluster at the new energy generator end is connected according to the capacitance value until the new energy transmission power reaches the power threshold, including setting an active power slope limit so that the new energy transmission power gradually increases according to the active power slope limit.

5. A device for increasing the transmission power of new energy sources in a power system with a low short-circuit ratio, characterized in that, The device includes: The grid equivalent module is used to convert the new energy grid-connected system into a single-machine infinite system, and to determine the infinite power supply voltage, equivalent line resistance, and equivalent line inductance of the single-machine infinite system. The data acquisition module is used to acquire the generator terminal voltage, current active power, and current reactive power of the new energy source when the short-circuit ratio of the new energy grid-connected system is less than the set short-circuit ratio threshold. The incremental reactive power module is used to calculate the incremental reactive power to be invested by the new energy source when the generator terminal voltage is less than the set voltage threshold, based on the voltage threshold, current active power, current reactive power, infinite power supply voltage, equivalent line resistance, and equivalent line inductance. The voltage threshold is calibrated based on the new energy generator terminal voltage when the new energy transmission power reaches the power threshold. The reactive power capacitor module is used to calculate the capacitance value of the capacitor to be connected at the new energy generator end based on the incremental reactive power. The capacitor input module is used to input at least one capacitor in the capacitor cluster of the new energy generator according to the capacitance value, until the power transmitted by the new energy reaches the power threshold.

6. The system according to claim 5, characterized in that, When the terminal voltage is less than the set voltage threshold, the incremental reactive power module calculates the incremental reactive power to be injected from the new energy source based on the voltage threshold, current active power, current reactive power, infinite power supply voltage, equivalent line resistance, and equivalent line inductance. The calculation formula is as follows: ΔQ1=Q-Q1 In the formula, ΔQ1 is the incremental reactive power to be put into operation, P1 and Q1 are the current active power and current reactive power of the new energy generator terminal, respectively, U is the voltage threshold, Q is the reactive power when the voltage of the new energy generator terminal reaches the voltage threshold, and E, R, X and Z are the power supply voltage of the single-machine infinite system, the equivalent line resistance, the equivalent line inductance and the equivalent line impedance, respectively.

7. The system according to claim 5, characterized in that, The reactive power capacitor module calculates the capacitance value of the capacitor to be connected at the new energy generator end based on the incremental reactive power, and the calculation formula is as follows: In the formula, C is the capacitance value of the capacitor to be connected to the new energy generator terminal, and ω is the angular frequency.

8. The system according to claim 5, characterized in that, The capacitor input module inputs at least one capacitor in the capacitor cluster of the new energy generator according to the capacitance value until the new energy transmission power reaches the power threshold. This includes setting an active power slope limit so that the new energy transmission power gradually increases according to the active power slope limit.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps of the method as described in any one of claims 1-4.

10. An electronic device, characterized in that, include: processor; Memory used to store the processor's executable instructions; The processor is configured to read the executable instructions from the memory and execute the executable instructions to implement the steps of the method according to any one of claims 1-4.

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