A sensitive busbar protection method and protection system based on time-domain differential admittance

Abstract

A sensitive busbar protection method and system based on time-domain differential admittance is disclosed. This method involves real-time acquisition of the instantaneous values ​​of current and voltage in each branch of the busbar, calculating the busbar differential admittance, and triggering the busbar protection when the differential admittance exceeds a threshold value. This invention calculates the differential admittance by acquiring real-time values ​​of current and voltage in each branch of the busbar, and determines whether the busbar protection should operate by judging whether the differential admittance exceeds a set threshold. It does not require phasor extraction, is unaffected by system harmonics, and the disclosed busbar protection method has a fast operating speed and can adapt to new power systems.

Description

Technical Field

[0001] This invention belongs to the field of relay protection technology, and relates to a bus protection method and system, particularly a bus protection method and system based on differential admittance. Background Technology

[0002] In new power system scenarios, especially in scenarios with dual-ended power electronic equipment, the fault current exhibits obvious weak feedback and through-current characteristics during bus faults, and the system has a large harmonic content. This causes the traditional bus protection principle based on phasors to suffer from reduced sensitivity or even become unsuitable.

[0003] Chinese patent application CN202211174786.X discloses a method and apparatus for constructing bus protection criteria in a high-proportion renewable energy system, comprising: acquiring bus polarization current and operating current; the bus polarization current including bus susceptance polarization current and bus conductance polarization current; the operating current including bus susceptance operating current and bus conductance operating current; constructing a bus amplitude protection criterion based on the bus susceptance polarization current and bus susceptance operating current, and the transverse electrical characteristics of the bus; constructing a bus phase protection criterion based on the bus conductance polarization current and bus conductance operating current, and the transverse electrical characteristics of the bus; and constituting the bus protection criterion by combining the amplitude protection criterion and the phase protection criterion. However, this invention requires phasor extraction and is susceptible to the power supply characteristics of new power systems, especially in the scenario of dual-ended power electronic equipment, where the fault current exhibits obvious weak feedback and through-current characteristics during bus faults, and the system harmonic content is relatively high, potentially leading to a decrease in sensitivity of this principle. Summary of the Invention

[0004] To address the issues in existing technologies where bus fault currents exhibit significant weak feedback and through-current characteristics in novel power system scenarios, resulting in high system harmonic content and consequently decreased sensitivity or even inapplicability of phasor-based bus protection principles, this invention provides a bus protection method and system for determining bus faults using instantaneous current and voltage values. This method eliminates the need for phasor extraction, is unaffected by harmonics, and resolves the problems disclosed in the background art.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A sensitive busbar protection method based on time-domain differential admittance, characterized in that the method includes the following steps:

[0007] Step 1: Collect the instantaneous values ​​of current in each branch of the busbar and the busbar voltage;

[0008] Step 2: Calculate the differential admittance Y of the busbar;

[0009] Step 3: When the bus differential admittance is greater than the differential admittance threshold value Y set If the busbar protection activates, the busbar protection will activate; otherwise, return to step 1.

[0010] The present invention further includes the following preferred embodiments:

[0011] More preferably,

[0012] In step 1, the current in each branch of the busbar includes the current in all branches connected to the busbar.

[0013] More preferably,

[0014] In step 2, the bus differential admittance Y is the ratio of the bus differential current to the bus voltage.

[0015] More preferably,

[0016] In step 2, the bus differential admittance Y is calculated as follows:

[0017]

[0018] Among them, i d Let represent the instantaneous differential current of the bus, u represent the instantaneous voltage of the bus, k represent the kth sampling point out of m sampling points, and Y represent the differential admittance of the bus.

[0019] More preferably,

[0020] Busbar instantaneous differential current i d The following formula is used to calculate:

[0021]

[0022] Among them, i n (k) is the instantaneous current sample value of the nth branch at the kth sampling point, where n is the nth branch among the p branches connected to the bus.

[0023] More preferably,

[0024] In step 3, when the bus differential admittance Y > Y set Busbar protection action, Y set This is the threshold value for the differential admittance that is being tuned.

[0025] More preferably,

[0026] The differential admittance threshold value Y set Set according to the admittance value corresponding to the maximum bus-to-ground capacitance.

[0027] This application also discloses a bus protection system based on time-domain differential admittance, including a branch current sampling module, a bus voltage sampling module, a differential admittance calculation module, and an action judgment module; characterized in that:

[0028] The branch current sampling module collects the instantaneous values ​​of the current in each branch of the bus, and the bus voltage sampling module collects the instantaneous values ​​of the bus voltage.

[0029] The differential admittance calculation module calculates the differential admittance Y based on the instantaneous values ​​of the current in each branch of the bus and the instantaneous value of the bus voltage; the action judgment module compares the calculated differential admittance Y with the differential admittance threshold value Y. set When Y > Y set At that time, the busbar protection activated.

[0030] More preferably,

[0031] The differential admittance module includes a bus instantaneous differential current calculation unit and a differential admittance calculation unit.

[0032] The bus instantaneous differential current calculation unit calculates the bus instantaneous differential current i according to the following formula. d :

[0033]

[0034] Among them, i n (k) is the instantaneous current sample value of the nth branch at the kth sampling point, where n is the nth branch out of a total of p branches of the bus.

[0035] The differential admittance calculation unit calculates the bus differential admittance Y according to the following formula:

[0036]

[0037] Among them, i d Let be the instantaneous differential current of the bus, u be the instantaneous voltage of the bus, and k be the k-th sampling point out of m sampling points. n Let Y be the instantaneous sampled value of the current in the nth branch, and Y be the differential admittance of the bus.

[0038] A computer-readable storage medium storing one or more programs, the one or more programs including instructions that, when executed by a computing device, cause the computing device to perform a bus protection method.

[0039] A computing device includes one or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and configured to be executed by the one or more processors, and the one or more programs include instructions for performing a bus protection method.

[0040] The beneficial effects achieved by this invention are as follows:

[0041] This invention calculates differential admittance by collecting instantaneous values ​​of bus protection current and voltage, and determines whether a bus fault has occurred by comparing the calculated differential admittance value with the setting threshold value, thereby improving the sensitivity of bus protection in new power system scenarios. Attached Figure Description

[0042] Figure 1 This is a flowchart of a bus protection method based on time-domain differential admittance. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The embodiments described in this application are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, other embodiments obtained by those skilled in the art without creative effort are all within the protection scope of this invention.

[0044] As attached Figure 1 As shown, this invention discloses a sensitive busbar protection method based on time-domain differential admittance, the method comprising the following steps:

[0045] Step 1: Collect the instantaneous values ​​of current in each branch of the busbar and the busbar voltage;

[0046] The current in each branch of the busbar includes the current in all branches connected to the busbar. It should be noted that if the bus tie circuit breaker is engaged, the branch includes the bus tie branch.

[0047] Step 2: Calculate the differential admittance Y of the busbar;

[0048] The bus differential admittance Y is calculated as follows:

[0049]

[0050] Among them, i d Let represent the instantaneous differential current of the bus, u represent the instantaneous voltage of the bus, k represent the kth sampling point out of m sampling points, and Y represent the differential admittance of the bus.

[0051] Among them, the instantaneous differential current i of the busbar d The following formula is used to calculate:

[0052]

[0053] Among them, i n (k) is the instantaneous current sample value of the nth branch at the kth sampling point, where n is the nth branch among the p branches connected to the bus.

[0054] Step 3: When the bus differential admittance is greater than the differential admittance threshold value Y set If the busbar protection activates, the busbar protection will activate; otherwise, return to step 1.

[0055] When the bus differential admittance Y > Y set Busbar protection action, Y set This is the threshold value for the differential admittance that is being tuned.

[0056] In a preferred embodiment of the present invention, the differential admittance threshold value Y set Set according to the admittance value corresponding to the maximum bus-to-ground capacitance.

[0057] This application also discloses a bus protection system based on time-domain differential admittance, including a branch current sampling module, a bus voltage sampling module, a differential admittance calculation module, and an action judgment module.

[0058] The branch current sampling module collects the instantaneous values ​​of the current in each branch of the bus, and the bus voltage sampling module collects the instantaneous values ​​of the bus voltage.

[0059] The differential admittance calculation module calculates the differential admittance Y based on the instantaneous values ​​of the current in each branch of the bus and the instantaneous value of the bus voltage;

[0060] The action judgment module will calculate the differential admittance Y and the differential admittance threshold Y. set When Y > Y set At that time, the busbar protection activated.

[0061] The differential admittance module includes a bus instantaneous differential current calculation unit and a differential admittance calculation unit.

[0062] The bus instantaneous differential current calculation unit calculates the bus instantaneous differential current i according to the following formula. d :

[0063]

[0064] Among them, i n (k) is the instantaneous current sample value of the nth branch at the kth sampling point, where n is the nth branch out of a total of p branches of the bus.

[0065] The differential admittance calculation unit calculates the bus differential admittance Y according to the following formula:

[0066]

[0067] Among them, i d Let be the instantaneous differential current of the bus, u be the instantaneous voltage of the bus, and k be the k-th sampling point out of m sampling points. n Let Y be the instantaneous sampled value of the current in the nth branch, and Y be the differential admittance of the bus.

[0068] Examples: The examples are only used to illustrate the technical solutions of the present invention more clearly, and should not be used to limit the scope of protection of the present invention.

[0069] This invention takes a high-resistivity fault in the A-phase occurrence zone of a single busbar with two branches as an example, and proposes a sensitive busbar protection method based on time-domain differential admittance, comprising the following steps:

[0070] Step 1: Collect the instantaneous current values ​​and instantaneous voltage values ​​of the two branches of the busbar. Collect 40 sampling points continuously.

[0071]

[0072]

[0073] Step 2: Calculate the instantaneous differential current of the busbar according to the formula, with a total of 40 points.

[0074]

[0075] Among them, i d For the instantaneous differential current of the bus, i n is the instantaneous sampled value of the current of the nth branch out of the two branches of the busbar, and k is the kth sampled point out of the 40 sampled points.

[0076]

[0077]

[0078] Step 3: Calculate the differential admittance according to the formula.

[0079]

[0080] Where Y is the differential admittance, i d denoted as bus instantaneous differential current, u as bus instantaneous voltage, and k as the kth sampling point out of 40 sampling points.

[0081] The calculated value is Y = 0.0352S.

[0082] Step 4: Compare the calculated differential admittance with the set differential admittance threshold value. The set value is the admittance value corresponding to a 0.1uF capacitor, which is 3.14E-5S. It can be seen that the calculated differential admittance is greater than the set admittance threshold, so the protection will operate.

[0083] Based on the same technical solution, the present invention also discloses a computer-readable storage medium storing one or more programs, the one or more programs including instructions that, when executed by a computing device, cause the computing device to perform a bus protection method based on time-domain differential admittance.

[0084] Based on the same technical solution, the present invention also discloses a computing device, including one or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and configured to be executed by the one or more processors, and the one or more programs include instructions for executing a bus protection method based on time-domain differential admittance.

[0085] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0086] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts 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, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0087] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0088] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A sensitive busbar protection method based on time-domain differential admittance, characterized in that, The method includes the following steps: Step 1: Collect the instantaneous values ​​of current in each branch of the busbar and the busbar voltage; Step 2: Calculate the differential admittance Y of the busbar; Among them, i d Let be the instantaneous differential current of the bus, u be the instantaneous voltage of the bus, k be the kth sampling point out of m sampling points, and Y be the differential admittance of the bus. Step 3: When the bus differential admittance is greater than the differential admittance threshold value Y set If the busbar protection activates, the busbar protection will activate; otherwise, return to step 1.

2. The sensitive bus protection method based on time-domain differential admittance according to claim 1, characterized in that: In step 1, the current in each branch of the busbar includes the current in all branches connected to the busbar.

3. The sensitive bus protection method based on time-domain differential admittance according to claim 1, characterized in that: Busbar instantaneous differential current i d The following formula is used to calculate: Among them, i n (k) is the instantaneous current sample value of the nth branch at the kth sampling point, where n is the nth branch among the p branches connected to the bus.

4. The sensitive bus protection method based on time-domain differential admittance according to claim 1, characterized in that: In step 3, when the bus differential admittance Y > Y set Busbar protection action, Y set This is the threshold value for the differential admittance that is being tuned.

5. The sensitive bus protection method based on time-domain differential admittance according to claim 4, characterized in that: The differential admittance threshold value Y set Set according to the admittance value corresponding to the maximum bus-to-ground capacitance.

6. A bus protection system based on the bus protection method according to any one of claims 1-5, comprising a branch current sampling module, a bus voltage sampling module, a differential admittance calculation module, and an action judgment module; characterized in that: The branch current sampling module collects the instantaneous values ​​of the current in each branch of the bus, and the bus voltage sampling module collects the instantaneous values ​​of the bus voltage. The differential admittance calculation module calculates the differential admittance Y based on the instantaneous values ​​of the current in each branch of the bus and the instantaneous value of the bus voltage; The action judgment module will calculate the differential admittance Y and the differential admittance threshold Y. set When Y>Y set At that time, the busbar protection activated.

7. The busbar protection system according to claim 6, characterized in that: The differential admittance module includes a bus instantaneous differential current calculation unit and a differential admittance calculation unit; The bus instantaneous differential current calculation unit calculates the bus instantaneous differential current i according to the following formula. d : Among them, i n (k) is the instantaneous sampled value of the current of the nth branch at the kth sampling point, where n is the nth branch among the p branches connected to the bus. The differential admittance calculation unit calculates the bus differential admittance Y according to the following formula: Among them, i d Let u be the instantaneous differential current of the bus, u be the instantaneous voltage of the bus, k be the kth sampling point out of m sampling points, and i be the instantaneous differential current of the bus. n Let Y be the instantaneous sampled value of the current in the nth branch, and Y be the differential admittance of the bus.

8. A computer-readable storage medium for storing one or more programs, characterized in that, The one or more programs include instructions that, when executed by a computing device, cause the computing device to perform any of the methods according to claims 1-5.

9. A computing device, characterized in that, include: One or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and configured to be executed by the one or more processors, the one or more programs including instructions for performing any of the methods according to claims 1-5.

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