A method for evaluating the safety margin of a secondary protection device and a medium

Abstract

The application relates to a safety margin evaluation method of a secondary protection device, which comprises the following steps: sampling an action amount and a braking amount of a protection action of the secondary protection device; calculating an unbiased sensitivity coefficient and a biased sensitivity coefficient according to a sensitivity coefficient definition formula of the secondary protection device and precision variation of sampling; calculating a maximum bias of the corresponding sensitivity of the secondary protection device according to the unbiased sensitivity coefficient and the biased sensitivity coefficient; calculating an unbiased sensitivity safety margin and a biased sensitivity safety margin according to the unbiased sensitivity coefficient, the biased sensitivity coefficient and a sensitivity coefficient checking limit value of the secondary protection device; and calculating a sensitivity safety margin reduction value of the secondary protection device according to the unbiased sensitivity safety margin and the biased sensitivity safety margin.

Description

Technical Field

[0001] This invention relates to the field of relay protection technology, and in particular to a method and medium for assessing the safety margin of a secondary protection device. Background Technology

[0002] Substation electrical equipment includes primary and secondary equipment. Primary equipment, also known as main equipment, constitutes the core of the power system and directly generates, transmits, and distributes electrical energy. This includes generators, transformers, circuit breakers, power busbars, and transmission lines. Secondary equipment controls, regulates, protects, and monitors the primary equipment. This includes control devices, relay protection systems, automatic monitoring systems, and measuring instruments. Secondary equipment is connected to the primary equipment via voltage transformers and current transformers.

[0003] The inventors of this application discovered in their research that, in terms of system analysis, safety margin assessment for primary equipment can provide maintenance suggestions and timely warnings of equipment defects, ensuring stable system operation. However, the safety margin assessment of secondary protection devices for relay protection that protect primary equipment is severely lagging behind. Especially with the application of smart relay networks, it is necessary to provide a dedicated safety margin assessment method for relay protection. Summary of the Invention

[0004] To address the aforementioned problems, the purpose of this invention is to provide a safety margin assessment method for secondary protection devices, which can provide timely safety margin assessments for secondary protection devices and ensure the safe and stable operation of the power grid.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, this application provides a method for assessing the safety margin of a secondary protection device, the method comprising:

[0007] The action and braking quantities of the secondary protection device are sampled.

[0008] Based on the definition formula of the sensitivity coefficient of the secondary protection device and the change in sampling accuracy, calculate the unbiased sensitivity coefficient and the biased sensitivity coefficient.

[0009] Based on the unbiased sensitivity coefficient and the biased sensitivity coefficient, calculate the maximum sensitivity deviation corresponding to the secondary protection device;

[0010] Based on the unbiased sensitivity coefficient, the biased sensitivity coefficient, and the sensitivity coefficient verification limit of the secondary protection device, calculate the unbiased sensitivity safety margin and the biased sensitivity safety margin.

[0011] The sensitivity safety margin reduction value of the secondary protection device is calculated based on the unbiased sensitivity safety margin and the biased sensitivity safety margin.

[0012] In one implementation of this application, the sensitivity coefficient of the secondary protection device is defined by the following formula:

[0013]

[0014] Among them, K sen This is the sensitivity coefficient.

[0015] In one implementation of this application, sampling the action and braking amounts of the secondary protection device includes:

[0016] Based on the protection type of the secondary protection device, the action amount and braking amount of the protection action are sampled.

[0017] In one implementation of this application, the protection type, depending on the protected object of the secondary protection device, includes line longitudinal differential protection, line zero-sequence protection, bus longitudinal linkage protection, and transformer protection.

[0018] In one implementation of this application, the method includes:

[0019] Calculate the unbiased sensitivity coefficient K based on the variation in sampling accuracy. senn And the biased sensitivity coefficient K sene .

[0020] In one implementation of this application, according to the formula

[0021]

[0022] Calculate the maximum sensitivity deviation ΔK.

[0023] In one implementation of this application, the sensitivity safety margin is determined according to the formula...

[0024]

[0025] Calculate and use it as the sensitivity safety margin M of the secondary protection device, where K lim The sensitivity coefficient verification limit for the secondary protection device.

[0026] In one implementation of this application, an unbiased sensitivity safety margin M is calculated based on the definition of the sensitivity safety margin. n and the safety margin M of biased sensitivity e .

[0027] In one implementation of this application, calculating the decrease in sensitivity safety margin of the secondary protection device based on the unbiased sensitivity safety margin and the biased sensitivity safety margin includes:

[0028] According to the formula

[0029] △M=M n -M e

[0030] Calculate the decrease in sensitivity safety margin ΔM.

[0031] Secondly, this application provides a computer-readable storage medium storing a computer program, which, when executed, controls the device containing the computer-readable storage medium to perform the safety margin assessment method for the secondary protection device described in the first aspect.

[0032] The present invention has the following advantages due to the adoption of the above technical solutions: In the present invention, the action amount and braking amount of the protection action of the secondary protection device are sampled, and the unbiased sensitivity coefficient and the biased sensitivity coefficient are calculated according to the sensitivity coefficient definition formula. Then, the maximum sensitivity deviation is calculated based on the unbiased sensitivity coefficient and the biased sensitivity coefficient. Based on the unbiased sensitivity coefficient and the biased sensitivity coefficient, as well as the sensitivity coefficient check limit of the secondary protection device, the unbiased sensitivity safety margin and the biased sensitivity safety margin are calculated. Based on the unbiased sensitivity safety margin and the biased sensitivity safety margin, the sensitivity safety margin reduction value of the secondary protection device is calculated. Thus, the safety margin of the secondary protection device can be evaluated through the maximum sensitivity deviation, the sensitivity safety margin, and the sensitivity safety margin reduction value. Attached Figure Description

[0033] Figure 1 This is a flowchart illustrating a safety margin assessment method for a secondary protection device provided in an embodiment of this application. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0035] To address the difficulty of timely assessment of the safety margin of secondary protection devices using existing technologies, this application provides a method and medium for assessing the safety margin of secondary protection devices. The method includes: sampling the action and braking quantities of the protection actions of the secondary protection device; calculating an unbiased sensitivity coefficient and a biased sensitivity coefficient based on the definition formula of the sensitivity coefficient of the secondary protection device and the variation in sampling accuracy; calculating the maximum sensitivity deviation of the secondary protection device based on the unbiased and biased sensitivity coefficients; calculating the unbiased sensitivity safety margin and the biased sensitivity safety margin based on the unbiased and biased sensitivity coefficients and the sensitivity coefficient verification limit of the secondary protection device; and calculating the sensitivity safety margin reduction value of the secondary protection device based on the unbiased and biased sensitivity safety margins. This application can provide timely safety margin assessments for secondary protection devices, ensuring the safe and stable operation of the power grid.

[0036] Please see Figure 1 In one aspect of the embodiments of this application, a method for evaluating the safety margin of a secondary protection device is provided.

[0037] The method described in this application embodiment includes the following steps:

[0038] S1, sample the action amount and braking amount of the protection action of the secondary protection device;

[0039] S2, based on the definition formula of the sensitivity coefficient of the secondary protection device and the change in sampling accuracy, calculate the unbiased sensitivity coefficient and the biased sensitivity coefficient.

[0040] Specifically, the formula for defining the sensitivity coefficient of the secondary protection device is as follows:

[0041]

[0042] Among them, K sen This is the sensitivity coefficient.

[0043] Therefore, the unbiased sensitivity coefficient K is calculated based on the change in sampling accuracy. senn And the biased sensitivity coefficient K sene .

[0044] S3, Calculate the maximum sensitivity deviation of the secondary protection device based on the unbiased sensitivity coefficient and the biased sensitivity coefficient;

[0045] Specifically, it can be determined according to the formula.

[0046]

[0047] Calculate the maximum sensitivity deviation ΔK.

[0048] S4. Calculate the safety margin of the unbiased sensitivity and the safety margin of the biased sensitivity based on the unbiased sensitivity coefficient, the biased sensitivity coefficient, and the sensitivity coefficient verification limit of the secondary protection device.

[0049] Specifically, define the sensitivity safety margin of the secondary protection device.

[0050]

[0051] Referring to the above formula, the unbiased sensitivity safety margin can be calculated as M. n The safety margin for biased sensitivity is M. e .

[0052] S5. Calculate the decrease in sensitivity safety margin of the secondary protection device based on the unbiased sensitivity safety margin and the biased sensitivity safety margin.

[0053] Specifically, according to the formula

[0054] △M=M n -M e

[0055] Calculate the decrease in sensitivity safety margin ΔM.

[0056] The secondary protection safety margin assessment method of this application can be used to assess the safety margin of secondary protection devices for line longitudinal differential protection, line zero-sequence protection, bus longitudinal linkage protection, and transformer protection.

[0057] Regarding the longitudinal differential protection of the line, we can obtain:

[0058]

[0059]

[0060]

[0061] △M=M n -M e

[0062] in, For operating current, K is the braking current, and K is the braking coefficient. lim This is a sensitivity calibration limitation.

[0063] Regarding zero-sequence protection, we can obtain:

[0064]

[0065]

[0066]

[0067] △M=M n -M e

[0068] in, For zero-sequence current, K lim This is a sensitivity calibration limitation.

[0069] For busbar longitudinal protection, we can obtain:

[0070]

[0071]

[0072]

[0073] △M=M n -M e

[0074] in, For operating current, K is the braking current, and K is the braking coefficient. lim This is a sensitivity calibration limitation.

[0075] Regarding transformer protection, we can obtain:

[0076]

[0077]

[0078]

[0079] △M=M n -M e

[0080] in, For operating current, K is the braking current, K1 is the braking coefficient, K lim This is a sensitivity calibration limitation.

[0081] In summary, the present invention samples the action and braking quantities of the secondary protection device. Based on the sensitivity coefficient definition formula, it calculates the unbiased and biased sensitivity coefficients. Then, based on the unbiased and biased sensitivity coefficients, it calculates the maximum sensitivity deviation. Based on the unbiased and biased sensitivity coefficients, and the sensitivity coefficient verification limit of the secondary protection device, it calculates the unbiased and biased sensitivity safety margins. Finally, based on the unbiased and biased sensitivity safety margins, it calculates the sensitivity safety margin reduction value of the secondary protection device. Thus, the safety margin of the secondary protection device can be evaluated using the maximum sensitivity deviation, the sensitivity safety margin, and the sensitivity safety margin reduction value.

[0082] In the several embodiments provided by this invention, it should be understood that the disclosed methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative; for instance, the division of the units described above is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0083] The integrated units implemented as software functional units described above can be stored in a computer-readable storage medium. These software functional units, stored in a storage medium, include several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute some steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0084] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for assessing the safety margin of a secondary protection device, characterized in that, The method includes: The action and braking quantities of the secondary protection device are sampled. Based on the definition formula of the sensitivity coefficient of the secondary protection device and the change in sampling accuracy, calculate the unbiased sensitivity coefficient and the biased sensitivity coefficient. Based on the unbiased sensitivity coefficient and the biased sensitivity coefficient, calculate the maximum sensitivity deviation corresponding to the secondary protection device; Based on the unbiased sensitivity coefficient, the biased sensitivity coefficient, and the sensitivity coefficient verification limit of the secondary protection device, calculate the unbiased sensitivity safety margin and the biased sensitivity safety margin. The sensitivity safety margin reduction value of the secondary protection device is calculated based on the unbiased sensitivity safety margin and the biased sensitivity safety margin. The sensitivity coefficient of the secondary protection device is defined by the following formula: ， in, This is the sensitivity coefficient; The method includes: calculating an unbiased sensitivity coefficient based on the variation in the sampling accuracy. And the biased sensitivity coefficient ; According to the formula Calculate the maximum sensitivity deviation ; The sensitivity safety margin is determined according to the formula... Calculated and used as the sensitivity safety margin of the secondary protection device. ,in, The sensitivity coefficient verification limit for the secondary protection device.

2. The safety margin assessment method for secondary protection devices according to claim 1, characterized in that, The sampling of the action and braking quantities of the secondary protection device includes: Based on the protection type of the secondary protection device, the action amount and braking amount of the protection action are sampled.

3. The safety margin assessment method for secondary protection devices according to claim 2, characterized in that, The protection type, depending on the protected object of the secondary protection device, includes line longitudinal differential protection, line zero-sequence protection, busbar longitudinal protection, and transformer protection.

4. The safety margin assessment method for secondary protection devices according to claim 1, characterized in that, Based on the definition of the sensitivity safety margin, calculate the unbiased sensitivity safety margin. and safety margin of biased sensitivity .

5. The safety margin assessment method for secondary protection devices according to claim 4, characterized in that, The calculation of the sensitivity safety margin reduction value of the secondary protection device based on the unbiased sensitivity safety margin and the biased sensitivity safety margin includes: According to the formula Calculate the decrease in the sensitivity safety margin. .

6. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, which, when executed, controls the device containing the computer-readable storage medium to perform the safety margin assessment method for the secondary protection device according to any one of claims 1 to 5.

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