Method and system for calculating active power of different-frequency different-amplitude voltage nodes and related equipment

Abstract

The invention relates to the technical field of power electronics, in particular to a method and system for calculating active power of different-frequency different-amplitude voltage nodes and related equipment. The method comprises the following steps: constructing a current differential equation of voltage nodes with different frequencies and amplitudes; solving a current differential equation of the voltage nodes with different frequencies and amplitudes to obtain phase current between the voltage nodes with different frequencies and amplitudes; constructing a power calculation formula of the voltage nodes with different frequencies and amplitudes according to the phase current between the voltage nodes with different frequencies and amplitudes; and inputting the frequency and the amplitude of the corresponding voltage node, and calculating the active power of the different-frequency different-amplitude voltage node through a power calculation formula.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular to a method, system and related equipment for calculating active power of voltage nodes with different frequencies and amplitudes. Background Art

[0002] As the proportion of new energy access in the power grid increases, the power system gradually shows the characteristics of power electronics, the system equivalent inertia and damping decrease, and voltage nodes with different frequencies and amplitudes may exist in the power grid under transient conditions. The current power transmission formula is based on the quasi-steady-state assumption of frequency synchronization, that is, it is derived under the condition of a stable phase difference. The power flow transmission mechanism between different-frequency voltage nodes is still unclear, and the phasor method is no longer applicable at this time. To address this gap, the present invention provides a method, system and related equipment for calculating the active power of different-frequency and different-amplitude voltage nodes. Summary of the Invention

[0003] To address the problems in the prior art, the present invention provides a method, system, and related equipment for calculating the active power of voltage nodes with different frequencies and amplitudes. The specific technical solution is as follows:

[0004] A method for calculating active power of voltage nodes with different frequencies and amplitudes, comprising the following steps:

[0005] Step S1, constructing current differential equations of voltage nodes with different frequencies and amplitudes;

[0006] Step S2, solving the current differential equations of the voltage nodes with different frequencies and amplitudes to obtain the phase currents between the voltage nodes with different frequencies and amplitudes;

[0007] Step S3, constructing a power calculation formula for voltage nodes with different frequencies and amplitudes based on the phase currents between voltage nodes with different frequencies and amplitudes;

[0008] Step S4: input the frequency and amplitude of the corresponding voltage node, and calculate the active power of the voltage node with different frequency and amplitude using the power calculation formula.

[0009] Preferably, the step S1 specifically includes the following steps:

[0010] Assume that the instantaneous voltage of phase a at node 1 and node 2 is v 1_a and v 2_a Respectively expressed as:

[0011]

[0012] Where V1 and V2 are the voltage amplitudes of nodes 1 and 2, ω1 and ω2 are the voltage frequencies of nodes 1 and 2, respectively. and are the initial phases of the voltages at nodes 1 and 2, respectively;

[0013] Considering that the line inductance and resistance between node 1 and node 2 are L 21 and R 21 , then the phase a current i from node 2 to node 1 is 21_a It is expressed as the differential equation shown in formula (3):

[0014]

[0015] Preferably, solving the current differential equations of voltage nodes of different frequencies and amplitudes in step S2 includes:

[0016] First, find the solution of the corresponding homogeneous equation, and then use the constant variation method to solve the current differential equation.

[0017] Preferably, the step S2 specifically includes the following steps:

[0018] Construct the homogeneous equation corresponding to the current differential equation, specifically:

[0019]

[0020] Solving the homogeneous equation (4) yields:

[0021]

[0022] Where C(t) is the variable to be determined. Further simplification yields:

[0023]

[0024] Substituting formula (6) back into the original nonhomogeneous equation (3), we can obtain:

[0025]

[0026] Further simplifying formula (7) yields:

[0027]

[0028] By taking the indefinite integral of both ends of formula (8) at the same time, we can get:

[0029]

[0030] Solving formula (9) yields the following variable C(t):

[0031]

[0032] Substituting formula (11) into formula (6) can obtain the instantaneous current i of phase a between node 2 and node 1 that satisfies formula (3): 21_a (t) is:

[0033]

[0034] Assuming the three-phase system is balanced, the instantaneous currents i between phases b and c between node 2 and node 1 are 21_b (t) and i 21_c (t) are:

[0035]

[0036] Preferably, solving equation (9) involves solving e at Solve the indefinite integral of sint, where a is R 21 / L 21 , we can know from the method of integration by parts:

[0037]

[0038] Combining formula (9) and formula (10), the time variable C(t) can be solved.

[0039] Preferably, the power calculation formula for voltage nodes with different frequencies and amplitudes in step S3 is:

[0040]

[0041] Substitute the current expressions in formulas (12)-(14) into i in (15) 21_a (t), i 21_b (t) and i 21_c (t) can be obtained:

[0042]

[0043] Preferably, it also includes simplifying formula (16), taking into account the following trigonometric identities:

[0044]

[0045] Where x and y are arbitrary expressions;

[0046] Then formula (16) can be simplified as:

[0047]

[0048] A system for calculating active power of voltage nodes with different frequencies and amplitudes, applied to the method described, comprising:

[0049] Current differential equation building module, used to build current differential equations for voltage nodes of different frequencies and amplitudes;

[0050] A current differential equation solving module is used to solve the current differential equations of voltage nodes with different frequencies and amplitudes to obtain the phase currents between voltage nodes with different frequencies and amplitudes;

[0051] A power calculation formula construction module is used to construct power calculation formulas for voltage nodes of different frequencies and amplitudes based on phase currents between voltage nodes of different frequencies and amplitudes;

[0052] The power calculation module is used to input the frequency and amplitude of the corresponding voltage node and calculate the active power of the voltage node with different frequency and amplitude through the power calculation formula.

[0053] A computer-readable storage medium includes a stored program, wherein when the program is run, the device where the computer-readable storage medium is located is controlled to execute the method for calculating the active power of voltage nodes with different frequencies and amplitudes.

[0054] A processor is used to run a program, wherein the program executes the method for calculating the active power of voltage nodes with different frequencies and amplitudes when running.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] The present invention realizes the accurate analysis of active power under transient conditions of power electronic power system, and the accuracy is greatly improved compared with the existing quasi-steady-state formula, which facilitates the accurate control of active power flow in power electronic power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly describes the drawings required for the specific embodiments or the description of the prior art. Similar elements or parts are generally identified by similar reference numerals throughout the drawings. Elements or parts in the drawings are not necessarily drawn to scale.

[0058] Figure 1 Flow chart of the method of the present invention.

[0059] Figure 2 This is a system principle diagram of the present invention. DETAILED DESCRIPTION

[0060] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0061] It will be understood that when used in this specification and the appended claims, the terms “comprises” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0062] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0063] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0064] Example 1:

[0065] like Figure 1 As shown, this embodiment provides a method for calculating the active power of voltage nodes with different frequencies and amplitudes, including the following steps:

[0066] Step S1: construct current differential equations for voltage nodes of different frequencies and amplitudes. Specifically, the following steps are included:

[0067] Assume that the instantaneous voltage of phase a at node 1 and node 2 is v 1_a and v 2_a Respectively expressed as:

[0068]

[0069] Where V1 and V2 are the voltage amplitudes of nodes 1 and 2, ω1 and ω2 are the voltage frequencies of nodes 1 and 2, respectively. and are the initial phases of the voltages at nodes 1 and 2, respectively;

[0070] Considering that the line inductance and resistance between node 1 and node 2 are L 21 and R 21 , then the phase a current i from node 2 to node 1 is 21_a It is expressed as the differential equation shown in formula (3):

[0071]

[0072] Step S2, solving the current differential equations of the voltage nodes with different frequencies and amplitudes to obtain the phase currents between the voltage nodes with different frequencies and amplitudes. Solving the current differential equations of the voltage nodes with different frequencies and amplitudes includes:

[0073] First, find the solution of the corresponding homogeneous equation, and then use the constant variation method to solve the current differential equation. The details are as follows:

[0074] Construct the homogeneous equation corresponding to the current differential equation, specifically:

[0075]

[0076] Solving the homogeneous equation (4) yields:

[0077]

[0078] Where C(t) is the variable to be determined. Further simplification yields:

[0079]

[0080] Substituting formula (6) back into the original nonhomogeneous equation (3), we can obtain:

[0081]

[0082] Further simplifying formula (7) yields:

[0083]

[0084] By taking the indefinite integral of both ends of formula (8) at the same time, we can get:

[0085]

[0086] Solving formula (9) involves solving e at Solve the indefinite integral of sint, where a is R 21 / L 21 , we can know from the method of integration by parts:

[0087]

[0088] Combining formula (9) and formula (10), the time variable C(t) can be solved.

[0089] Solving formula (9) yields the following variable C(t):

[0090]

[0091] Substituting formula (11) into formula (6) can obtain the instantaneous current i of phase a between node 2 and node 1 that satisfies formula (3): 21_a (t) is:

[0092]

[0093] Assuming the three-phase system is balanced, the instantaneous currents i between phases b and c between node 2 and node 1 are 21_b (t) and i 21_c (t) are:

[0094] Step S3, constructing a power calculation formula for voltage nodes with different frequencies and amplitudes based on the phase currents between voltage nodes with different frequencies and amplitudes;

[0095] Power calculation formula for voltage nodes of different frequencies and amplitudes

[0096]

[0097] Substitute the current expressions in formulas (12)-(14) into i in (15) 21_a (t), i 21_b (t) and i 21_c (t) can be obtained:

[0098]

[0099] It also includes simplifying formula (16), taking into account the following trigonometric identities:

[0100]

[0101] Where x and y are arbitrary expressions;

[0102] Then formula (16) can be simplified as:

[0103]

[0104] Step S4: input the frequency and amplitude of the corresponding voltage node, and calculate the active power of the voltage node with different frequency and amplitude using the power calculation formula.

[0105] Example 2:

[0106] like Figure 2 As shown, based on the same inventive concept as that of Example 1, this embodiment provides a system for calculating active power of voltage nodes with different frequencies and amplitudes, which is applied to the method described, including:

[0107] Current differential equation building module, used to build current differential equations for voltage nodes of different frequencies and amplitudes;

[0108] A current differential equation solving module is used to solve the current differential equations of voltage nodes with different frequencies and amplitudes to obtain the phase currents between voltage nodes with different frequencies and amplitudes;

[0109] A power calculation formula construction module is used to construct power calculation formulas for voltage nodes of different frequencies and amplitudes based on phase currents between voltage nodes of different frequencies and amplitudes;

[0110] The power calculation module is used to input the frequency and amplitude of the corresponding voltage node and calculate the active power of the voltage node with different frequency and amplitude through the power calculation formula.

[0111] Example 3:

[0112] Based on the same inventive concept as Example 1, this embodiment provides a computer-readable storage medium, which includes a stored program, wherein when the program is running, the device where the computer-readable storage medium is located is controlled to execute the method for calculating the active power of voltage nodes with different frequencies and amplitudes.

[0113] Example 4:

[0114] Based on the same inventive concept as that of Example 1, this embodiment provides a processor, which is used to run a program, wherein the method for calculating the active power of voltage nodes with different frequencies and amplitudes is executed when the program is run.

[0115] Those skilled in the art will appreciate that the modules of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition of each example has been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0116] In the embodiments provided by the present invention, it should be understood that the division of modules is merely a logical function division, and there may be other division methods in actual implementation, for example, multiple modules can be combined into one module, one module can be split into multiple modules, or some features can be ignored, etc.

[0117] In addition, the functional modules in various embodiments of the present invention may be integrated into a single processing module, or each module may exist physically separately, or two or more modules may be integrated into a single module. The aforementioned integrated modules may be implemented in the form of hardware or software functional modules.

[0118] If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server or network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-0nly Memory), random access memory (RAM, Random Access Memory), mobile hard disk, magnetic disk or optical disk, etc., various media that can store program code.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than 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 they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and description of the present invention.

Claims

1. A method for calculating active power of voltage nodes with different frequencies and amplitudes, characterized in that: The following steps are involved: Step S1, constructing current differential equations of voltage nodes with different frequencies and amplitudes; Step S2, solving the current differential equations of the voltage nodes with different frequencies and amplitudes to obtain the phase currents between the voltage nodes with different frequencies and amplitudes; Step S3, constructing a power calculation formula for voltage nodes with different frequencies and amplitudes based on the phase currents between voltage nodes with different frequencies and amplitudes; Step S4: input the frequency and amplitude of the corresponding voltage node, and calculate the active power of the voltage node with different frequency and amplitude using the power calculation formula.

2. The method for calculating active power of voltage nodes with different frequencies and amplitudes according to claim 1, characterized in that: The step S1 specifically includes the following steps: Assume that the instantaneous voltage of phase a at node 1 and node 2 is v 1_a and v 2_a Respectively expressed as: Where V1 and V2 are the voltage amplitudes of nodes 1 and 2, ω1 and ω2 are the voltage frequencies of nodes 1 and 2, respectively. and are the initial phases of the voltages at nodes 1 and 2, respectively; Considering that the line inductance and resistance between node 1 and node 2 are L 21 and R 21 , then the a-phase current i from node 2 to node 1 is 21_a It is expressed as the differential equation shown in formula (3):

3. The method for calculating active power of voltage nodes with different frequencies and amplitudes according to claim 2, characterized in that: Solving the current differential equations of voltage nodes with different frequencies and amplitudes in step S2 includes: First, find the solution of the corresponding homogeneous equation, and then use the constant variation method to solve the current differential equation.

4. The method for calculating active power of voltage nodes with different frequencies and amplitudes according to claim 3, characterized in that: The step S2 specifically includes the following steps: Construct the homogeneous equation corresponding to the current differential equation, specifically: Solving the homogeneous equation (4) yields: Where C(t) is the variable to be determined. Further simplification yields: Substituting formula (6) back into the original nonhomogeneous equation (3), we can obtain: Further simplifying formula (7) yields: By taking the indefinite integral of both ends of formula (8) at the same time, we can get: Solving formula (9) yields the following variable C(t): Substituting formula (11) into formula (6) can obtain the instantaneous current i of phase a between node 2 and node 1 that satisfies formula (3): 21_a (t) is: Assuming the three-phase system is balanced, the instantaneous currents i between phases b and c between node 2 and node 1 are 21_b (t) and i 21_c (t) are:

5. The method for calculating active power of voltage nodes with different frequencies and amplitudes according to claim 4, characterized in that: Solving formula (9) involves solving e at Solve the indefinite integral of sint, where a is R 21 / L 21 , we can know from the method of integration by parts: Combining formula (9) and formula (10), the time variable C(t) can be solved.

6. The method for calculating active power of voltage nodes with different frequencies and amplitudes according to claim 4, characterized in that: The power calculation formula of the voltage nodes with different frequencies and amplitudes in step S3 is: Substitute the current expressions in formulas (12)-(14) into i in (15) 21_a (t), i 21_b (t) and i 21_c (t) can be obtained:

7. The method for calculating active power of voltage nodes with different frequencies and amplitudes according to claim 1, characterized in that: It also includes simplifying formula (16), taking into account the following trigonometric identities: Where x and y are arbitrary expressions; Then formula (16) can be simplified as:

8. A system for calculating active power of voltage nodes with different frequencies and amplitudes, characterized in that: The method applied to any one of claims 1 to 7, comprising: Current differential equation building module, used to build current differential equations for voltage nodes of different frequencies and amplitudes; A current differential equation solving module is used to solve the current differential equations of voltage nodes with different frequencies and amplitudes to obtain the phase currents between voltage nodes with different frequencies and amplitudes; A power calculation formula construction module is used to construct power calculation formulas for voltage nodes of different frequencies and amplitudes based on phase currents between voltage nodes of different frequencies and amplitudes; The power calculation module is used to input the frequency and amplitude of the corresponding voltage node and calculate the active power of the voltage node with different frequency and amplitude through the power calculation formula.

9. A computer-readable storage medium, characterized in that The computer-readable storage medium includes a stored program, wherein when the program is executed, the device where the computer-readable storage medium is located is controlled to execute the method for calculating the active power of voltage nodes with different frequencies and amplitudes according to any one of claims 1 to 7.

10. A processor, characterized in that: The processor is used to run a program, wherein the program, when running, executes the method for calculating the active power of voltage nodes with different frequencies and amplitudes as described in any one of claims 1 to 7.

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