New energy limit scale evaluation method and system considering influence of conventional direct current system

Abstract

The invention discloses a new energy limit scale evaluation method and system considering the influence of a conventional direct current system, and belongs to the technical field of new energy grid-connected scale evaluation of an alternating current and direct current hybrid system. The method comprises the following steps: respectively establishing a direct-current power transmission system analysis model and a new energy analysis model for a direct-current power transmission system of a power grid and reactive compensation equipment of a new energy station; according to the DC power transmission system analysis model, establishing a power grid equivalent model based on the DC power transmission system; and solving the grid-connected scale of the new energy limit for the new energy analysis model and the power grid equivalent model. The implementation of the invention is beneficial for power system planners to plan the new energy limit grid-connected scale according to the accessed direct current system.

Description

Technical Field

[0001] This invention relates to the field of new energy grid connection scale assessment technology for AC / DC hybrid systems, and more specifically, to a method and system for assessing the limit scale of new energy considering the influence of conventional DC systems. Background Technology

[0002] With the development of high-voltage direct current (HVDC) transmission technology, more and more HVDC transmission systems are being applied to the power grid; the proportion of renewable energy generation is also increasing. Both of these systems are primarily composed of power electronic equipment and lack reactive power support capabilities. To address this issue, filters are typically installed at renewable energy power plants and converter stations. However, the reactive power of these filters is affected by their voltage. If a voltage drop occurs, the reactive power of the filters decreases, causing the voltage to drop further, ultimately leading to voltage instability. Excessive grid connection scale of renewable energy is one of the main causes of this problem. However, current technology lacks a systematic and standardized method for handling the maximum grid connection scale of renewable energy. Summary of the Invention

[0003] To address the above problems, this invention proposes a method for assessing the maximum scale of new energy sources that considers the impact of conventional DC systems, comprising:

[0004] For the DC transmission system of the power grid and the reactive power compensation equipment of new energy power plants, analysis models of DC transmission system and new energy are established respectively.

[0005] Based on the aforementioned DC transmission system analysis model, an equivalent power grid model based on the DC transmission system is established;

[0006] For the aforementioned new energy analysis model and power grid equivalent model, the grid connection scale of the new energy limit is obtained.

[0007] Optional DC transmission system analysis models are as follows:

[0008]

[0009] Where P1 is the actual operating power of the DC transmission system, U is the voltage of the converter station bus, and R1 is the equivalent resistance of the DC transmission system, and R1∈(-∞,0).

[0010] Optional new energy analysis models are as follows:

[0011]

[0012] Where P represents the active power of the new energy source, and Q represents the reactive power compensation equipment analysis model of the new energy power station. The power factor.

[0013] Optional, power grid equivalent models include:

[0014] The Thevenin equivalent impedance is calculated as follows:

[0015]

[0016] The Thevenin equivalent potential is calculated as follows:

[0017]

[0018] Where Z0 is the equivalent impedance from the grid side to the DC system; R1 is the equivalent resistance of the DC system; Z is the impedance after the grid side and the DC system are equalized, Z∈(0,R0+jX0); E is the grid side voltage; E1 is the voltage after the grid side and the DC system are equalized;

[0019] in:

[0020]

[0021] Optionally, for the new energy analysis model and the power grid equivalent model, the grid connection scale of the new energy limit is obtained, including:

[0022] Based on the aforementioned new energy analysis model and power grid equivalent model, the calculation formula for the grid-connected scale of the new energy limit is established as follows:

[0023]

[0024] Among them, P MAX To account for the maximum grid-connected capacity of new energy sources after the DC system is implemented, E1 is the power factor, E1 is the voltage on the grid side after being equivalent to that of the DC system, X is the reactance of the Thevenin equivalent impedance, and R is the resistance of the Thevenin equivalent impedance.

[0025] when When there is no reactive power compensation within the new energy power station:

[0026]

[0027] At this time, if

[0028]

[0029] At this time, if

[0030]

[0031] when At that time, the reactive power compensation level within the new energy power station is considered to be 30% of the rated capacity:

[0032]

[0033] At this point, when R = 0:

[0034]

[0035] At this point, when R = R0:

[0036]

[0037] in:

[0038]

[0039] Furthermore, this invention proposes a new energy limit scale assessment system that considers the impact of conventional DC systems, comprising:

[0040] The first modeling module is used to establish analysis models for DC transmission systems and new energy sources, respectively, for the DC transmission system of the power grid and the reactive power compensation equipment of new energy power plants.

[0041] The second modeling module is used to establish an equivalent power grid model based on the DC transmission system according to the DC transmission system analysis model.

[0042] The output module is used to calculate the grid-connected scale of the new energy limit from the new energy analysis model and the power grid equivalent model.

[0043] Optional DC transmission system analysis models are as follows:

[0044]

[0045] Where P1 is the actual operating power of the DC transmission system, U is the voltage of the converter station bus, and R1 is the equivalent resistance of the DC transmission system, and R1∈(-∞,0).

[0046] Optional new energy analysis models are as follows:

[0047]

[0048] Where P represents the active power of new energy sources, and Q represents the reactive power compensation equipment analysis model of new energy power plants. The power factor.

[0049] Optional, equivalent power grid models include:

[0050] The Thevenin equivalent impedance is calculated as follows:

[0051]

[0052] The Thevenin equivalent potential is calculated as follows:

[0053]

[0054] Where Z0 is the equivalent impedance from the grid side to the DC system; R1 is the equivalent resistance of the DC system; Z is the impedance after the grid side and the DC system are equalized, Z∈(0,R0+jX0); E is the grid side voltage; E1 is the voltage after the grid side and the DC system are equalized;

[0055] in:

[0056]

[0057] Optionally, for the new energy analysis model and the power grid equivalent model, the grid connection scale of the new energy limit is obtained, including:

[0058] Based on the aforementioned new energy analysis model and power grid equivalent model, the calculation formula for the grid-connected scale of the new energy limit is established as follows:

[0059]

[0060] Among them, P MAX To account for the maximum grid-connected capacity of new energy sources after the DC system is implemented, E1 is the power factor, E1 is the voltage on the grid side after being equivalent to that of the DC system, X is the reactance of the Thevenin equivalent impedance, and R is the resistance of the Thevenin equivalent impedance.

[0061] when When there is no reactive power compensation within the new energy power station:

[0062]

[0063] At this time, if

[0064]

[0065] At this time, if

[0066]

[0067] when At that time, the reactive power compensation level within the new energy power station is considered to be 30% of the rated capacity:

[0068]

[0069] At this point, when R = 0:

[0070]

[0071] At this point, when R = R0:

[0072]

[0073] in:

[0074]

[0075] In another aspect, the present invention also provides a computing device, comprising: one or more processors;

[0076] A processor is used to execute one or more programs;

[0077] When the one or more programs are executed by the one or more processors, the method described above is implemented.

[0078] In another aspect, the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed, implements the method described above.

[0079] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0080] This invention provides a method for assessing the maximum grid-connected capacity of new energy sources, taking into account the impact of conventional DC systems. The method includes: establishing analytical models for the DC transmission system and new energy sources, respectively, for the DC transmission system of the power grid and the reactive power compensation equipment at new energy power plants; establishing an equivalent grid model based on the DC transmission system analytical model; and calculating the maximum grid-connected capacity of new energy sources from the new energy analysis model and the equivalent grid model. The implementation of this invention is beneficial for power system planners to plan the maximum grid-connected capacity of new energy sources based on the connected DC system. Attached Figure Description

[0081] Figure 1 This is a flowchart of the method of the present invention;

[0082] Figure 2 This is a structural diagram of the system of the present invention. Detailed Implementation

[0083] 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.

[0084] 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.

[0085] Example 1:

[0086] This invention proposes a method for assessing the maximum scale of new energy sources that considers the impact of conventional DC systems, such as... Figure 1 As shown, it includes:

[0087] Step 1: Establish analysis models for the DC transmission system and the new energy power plant reactive power compensation equipment, respectively.

[0088] Step 2: Based on the DC transmission system analysis model, establish an equivalent power grid model based on the DC transmission system;

[0089] Step 3: Calculate the grid connection scale of the new energy limit based on the new energy analysis model and the power grid equivalent model.

[0090] Steps 1-3 above mainly propose an analytical model for a direct current transmission system (HVDC);

[0091] An analytical model for reactive power compensation equipment in new energy power plants was proposed.

[0092] An equivalent power grid model considering DC transmission systems is proposed;

[0093] Among them, an analytical model for a direct current transmission system (HVDC) is proposed, including:

[0094] Based on the actual operating power of the DC transmission system, an analytical model is established:

[0095]

[0096] In the formula, P1 is the actual operating power of the DC transmission system, U is the voltage of the converter station bus, R1 is the equivalent resistance of the DC transmission system, and R1∈(-∞,0).

[0097] Among them, a reactive power compensation analysis model for new energy power plants is proposed, including:

[0098] Establish reactive power compensation measures that take into account the active power of new energy sources, and adopt a constant power factor control method, including:

[0099]

[0100] In the formula, P represents the active power of the new energy source, and Q represents the reactive power compensation equipment analysis model of the new energy power station. The power factor.

[0101] Among them, an equivalent power grid model considering DC transmission systems is proposed, including:

[0102] An equivalent model of the power grid considering the DC transmission system was established. First, the Thevenin equivalent of the power grid side was performed, including:

[0103] Thevenin equivalent impedance is:

[0104]

[0105] Thevenin equivalent potential is:

[0106]

[0107] In the formula, Z0 is the equivalent impedance from the grid side to the DC system; R1 is the equivalent resistance of the DC system; Z is the impedance after the grid side and the DC system are equalized, Z∈(0,R0+jX0); E is the grid side voltage; E1 is the voltage after the grid side and the DC system are equalized.

[0108] Among them, it is proposed to consider the transmission power from the DC system to the AC system for renewable energy, including:

[0109] Considering the transmission power from new energy sources in the DC system to the AC grid, the calculation method is as follows:

[0110] According to the trigonometric function sin 2 θ+cos 2 θ=1, establish U 2 The quadratic equation of :

[0111]

[0112] when Sometimes, At this point, P reaches its maximum value:

[0113]

[0114] In the formula, P MAX To take into account the maximum grid-connected capacity of new energy sources after the DC system is implemented.

[0115] Further simplification:

[0116]

[0117] when When there is no reactive power compensation within the new energy power station:

[0118]

[0119] At this time, if

[0120]

[0121] At this time, if

[0122]

[0123] when At that time, the reactive power compensation level within the new energy power station is considered to be 30% of the rated capacity:

[0124]

[0125] At this point, when R = 0:

[0126]

[0127] At this point, when R = R0:

[0128]

[0129] In summary,

[0130] Example 2:

[0131] This invention proposes a new energy limit scale assessment system 200 that considers the influence of conventional DC systems, such as... Figure 2 As shown, it includes:

[0132] The first modeling module 201 is used to establish analysis models for DC transmission systems and new energy sources, respectively, for DC transmission systems of power grids and reactive power compensation equipment of new energy power plants.

[0133] The second modeling module 202 is used to establish an equivalent power grid model based on the DC transmission system according to the DC transmission system analysis model;

[0134] The output module 203 is used to calculate the grid connection scale of the new energy limit from the new energy analysis model and the power grid equivalent model.

[0135] The analysis model for the DC transmission system is as follows:

[0136]

[0137] Where P1 is the actual operating power of the DC transmission system, U is the voltage of the converter station bus, and R1 is the equivalent resistance of the DC transmission system, and R1∈(-∞,0).

[0138] The new energy analysis model is as follows:

[0139]

[0140] Where P represents the active power of new energy sources, and Q represents the reactive power compensation equipment analysis model of new energy power plants. The power factor.

[0141] The equivalent model of the power grid includes:

[0142] The Thevenin equivalent impedance is calculated as follows:

[0143]

[0144] The Thevenin equivalent potential is calculated as follows:

[0145]

[0146] Where Z0 is the equivalent impedance from the grid side to the DC system; R1 is the equivalent resistance of the DC system; Z is the impedance after the grid side and the DC system are equalized, Z∈(0,R0+jX0); E is the grid side voltage; E1 is the voltage after the grid side and the DC system are equalized;

[0147] in:

[0148]

[0149] Specifically, for the aforementioned new energy analysis model and power grid equivalent model, the grid connection scale of the new energy limit is calculated, including:

[0150] Based on the aforementioned new energy analysis model and power grid equivalent model, the calculation formula for the grid-connected scale of the new energy limit is established as follows:

[0151]

[0152] Among them, P MAX To account for the maximum grid-connected capacity of new energy sources after the DC system is implemented, E1 is the power factor, E1 is the voltage on the grid side after being equivalent to that of the DC system, X is the reactance of the Thevenin equivalent impedance, and R is the resistance of the Thevenin equivalent impedance.

[0153] when When there is no reactive power compensation within the new energy power station:

[0154]

[0155] At this time, if

[0156]

[0157] At this time, if

[0158]

[0159] when At that time, the reactive power compensation level within the new energy power station is considered to be 30% of the rated capacity:

[0160]

[0161] At this point, when R = 0:

[0162]

[0163] At this point, when R = R0:

[0164]

[0165] in:

[0166]

[0167] This invention provides a quantitative analysis tool that helps power system planners to plan the maximum grid connection scale of new energy sources based on the DC system they are connected to.

[0168] Example 3:

[0169] Based on the same inventive concept, this invention also provides a computer device, which includes a processor and a memory. The memory stores a computer program, which includes program instructions. The processor executes the program instructions stored in the computer storage medium. The processor may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing and control core of the terminal, suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in the computer storage medium to implement corresponding method flows or corresponding functions, thereby implementing the steps of the methods in the above embodiments.

[0170] Example 4:

[0171] Based on the same inventive concept, this invention also provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device used to store programs and data. It is understood that the computer-readable storage medium here can include both the built-in storage medium in the computer device and extended storage media supported by the computer device. The computer-readable storage medium provides storage space that stores the terminal's operating system. Furthermore, this storage space also stores one or more instructions suitable for loading and execution by a processor. These instructions can be one or more computer programs (including program code). It should be noted that the computer-readable storage medium here can be high-speed RAM or non-volatile memory, such as at least one disk storage device. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the steps of the method in the above embodiments.

[0172] 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 implemented 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 solutions in the embodiments of the present invention can be implemented using various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0173] This 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 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, generate instructions for implementing 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.

[0174] 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.

[0175] 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.

[0176] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0177] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for assessing the maximum scale of new energy sources considering the impact of conventional DC systems, characterized in that, include: For the DC transmission system of the power grid and the reactive power compensation equipment of new energy power plants, analysis models of DC transmission system and new energy are established respectively. Based on the aforementioned DC transmission system analysis model, an equivalent power grid model based on the DC transmission system is established; For the aforementioned new energy analysis model and power grid equivalent model, the grid connection scale of the new energy limit is obtained.

2. The method for assessing the maximum scale of new energy sources according to claim 1, characterized in that, The analysis model of the DC transmission system is as follows: Where P1 is the actual operating power of the DC transmission system, U is the voltage of the converter station bus, and R1 is the equivalent resistance of the DC transmission system, and R1∈(-∞,0).

3. The method for assessing the maximum scale of new energy sources according to claim 1, characterized in that, The new energy analysis model is as follows: Where P represents the active power of new energy sources, and Q represents the reactive power compensation equipment analysis model of new energy power plants. The power factor.

4. The method for assessing the maximum scale of new energy sources according to claim 1, characterized in that, The power grid equivalent model includes: The Thevenin equivalent impedance is calculated as follows: The Thevenin equivalent potential is calculated as follows: Where Z0 is the equivalent impedance from the grid side to the DC system; R1 is the equivalent resistance of the DC system; Z is the equivalent impedance of the grid side and the DC system, Z∈(0,R0+jX0); E is the grid side voltage; E1 is the equivalent voltage of the grid side and the DC system. in:

5. The method for assessing the maximum scale of new energy sources according to claim 1, characterized in that, The determination of the grid-connected capacity of the new energy source limit using the new energy analysis model and the power grid equivalent model includes: Based on the aforementioned new energy analysis model and power grid equivalent model, the calculation formula for the grid-connected scale of the new energy limit is established as follows: Among them, P MAX To account for the maximum grid-connected capacity of new energy sources after the DC system is implemented, E1 is the power factor, E1 is the voltage on the grid side after being equivalent to that of the DC system, X is the reactance of the Thevenin equivalent impedance, and R is the resistance of the Thevenin equivalent impedance. when When there is no reactive power compensation within the new energy power station: At this time, if At this time, if when At that time, the reactive power compensation level within the new energy power station is considered to be 30% of the rated capacity: At this point, when R = 0: At this point, when R = R0: in:

6. A new energy limit scale assessment system considering the influence of conventional DC systems, characterized in that, include: The first modeling module is used to establish analysis models for DC transmission systems and new energy sources, respectively, for the DC transmission system of the power grid and the reactive power compensation equipment of new energy power plants. The second modeling module is used to establish an equivalent power grid model based on the DC transmission system according to the DC transmission system analysis model. The output module is used to calculate the grid-connected scale of the new energy limit from the new energy analysis model and the power grid equivalent model.

7. The new energy limit scale assessment system according to claim 6, characterized in that, The analysis model of the DC transmission system is as follows: Where P1 is the actual operating power of the DC transmission system, U is the voltage of the converter station bus, and R1 is the equivalent resistance of the DC transmission system, and R1∈(-∞,0).

8. The new energy limit scale assessment system according to claim 6, characterized in that, The new energy analysis model is as follows: Where P represents the active power of new energy sources, and Q represents the reactive power compensation equipment analysis model of new energy power plants. The power factor.

9. The new energy limit scale assessment system according to claim 6, characterized in that, The power grid equivalent model includes: The Thevenin equivalent impedance is calculated as follows: The Thevenin equivalent potential is calculated as follows: Where Z0 is the equivalent impedance from the grid side to the DC system; R1 is the equivalent resistance of the DC system; Z is the impedance after the grid side and the DC system are equalized, Z∈(0,R0+jX0); E is the grid side voltage; E1 is the voltage after the grid side and the DC system are equalized; in:

10. The new energy limit scale assessment system according to claim 6, characterized in that, The determination of the grid-connected capacity of the new energy source limit using the new energy analysis model and the power grid equivalent model includes: Based on the aforementioned new energy analysis model and power grid equivalent model, the calculation formula for the grid-connected scale of the new energy limit is established as follows: Among them, P MAX To account for the maximum grid-connected capacity of new energy sources after the DC system is implemented, E1 is the power factor, E1 is the voltage on the grid side after being equivalent to that of the DC system, X is the reactance of the Thevenin equivalent impedance, and R is the resistance of the Thevenin equivalent impedance. when When there is no reactive power compensation within the new energy power station: At this time, if At this time, if when At that time, the reactive power compensation level within the new energy power station is considered to be 30% of the rated capacity: At this point, when R = 0: At this point, when R = R0: in:

11. A computer device, characterized in that, include: One or more processors; A processor is used to execute one or more programs; When the one or more programs are executed by the one or more processors, the method described in any one of claims 1-5 is implemented.

12. A computer-readable storage medium, characterized in that, It contains a computer program, which, when executed, implements the method as described in any one of claims 1-5.

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